Eeschema object list and other minor improvements.

* Convert Eeschema from manually linked list to DLIST for storing SCH_ITEM objects. * Add helper functions to SCH_SCREEN for appending list of SCH_ITEM objects. * Fix bug in wire editing code for accurate undo/redo behavior. * Add member to DLIST to append another DLIST. * Other minor code cleaning.

Eeschema object list and other minor improvements.
* Convert Eeschema from manually linked list to DLIST for storing SCH_ITEM objects. * Add helper functions to SCH_SCREEN for appending list of SCH_ITEM objects. * Fix bug in wire editing code for accurate undo/redo behavior. * Add member to DLIST to append another DLIST. * Other minor code cleaning.
aaa1cc3e · Wayne Stambaugh · a1ff3261 · aaa1cc3e · aaa1cc3e · aaa1cc3e
Commit aaa1cc3e authored Feb 26, 2012 by Wayne Stambaugh
37 changed files
--- a/common/base_struct.cpp
+++ b/common/base_struct.cpp
@@ -2,7 +2,6 @@
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2004 Jean-Pierre Charras, jaen-pierre.charras@gipsa-lab.inpg.com
- * Copyright (C) 2008-20011 Wayne Stambaugh <stambaughw@verizon.net>
 * Copyright (C) 1992-2011 KiCad Developers, see AUTHORS.txt for contributors.
 *
 * This program is free software; you can redistribute it and/or
@@ -217,15 +216,14 @@ EDA_ITEM& EDA_ITEM::operator=( const EDA_ITEM& aItem )
 {
    if( &aItem != this )
    {
-        m_StructType = aItem.Type();
+        m_Image = aItem.m_Image;
-        Pnext = aItem.Pnext;
-        Pback = aItem.Pback;
        m_StructType = aItem.m_StructType;
        m_Parent = aItem.m_Parent;
        m_Son = aItem.m_Son;
        m_Flags = aItem.m_Flags;
-        SetTimeStamp( aItem.m_TimeStamp );
+        m_TimeStamp = aItem.m_TimeStamp;
        m_Status = aItem.m_Status;
+        m_forceVisible = aItem.m_forceVisible;
    }
    return *this;

--- a/common/dlist.cpp
+++ b/common/dlist.cpp
@@ -85,6 +85,36 @@ void DHEAD::append( EDA_ITEM* aNewElement )
 }
+void DHEAD::append( DHEAD& aList )
+{
+    wxCHECK_RET( aList.GetCount() != 0, wxT( "Attempt to append empty list." ) );
+    // Change the item's list to me.
+    for( EDA_ITEM* item = aList.first;  item != NULL;  item = item->Next() )
+        item->SetList( this );
+    if( first )       // list is not empty, set last item's next to the first item in aList
+    {
+        wxCHECK_RET( last != NULL, wxT( "Last list element not set." ) );
+        last->SetNext( aList.first );
+        aList.first->SetBack( last );
+        last = aList.last;
+    }
+    else              // list is empty, first and last are same as aList
+    {
+        first = aList.first;
+        last  = aList.last;
+    }
+    count += aList.count;
+    aList.count = 0;
+    aList.first = NULL;
+    aList.last = NULL;
+}
 void DHEAD::insert( EDA_ITEM* aNewElement, EDA_ITEM* aAfterMe )
 {
    wxASSERT( aNewElement != NULL );

--- a/common/sch_item_struct.cpp
+++ b/common/sch_item_struct.cpp
@@ -2,7 +2,6 @@
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2006 Jean-Pierre Charras, jaen-pierre.charras@gipsa-lab.inpg.com
- * Copyright (C) 2011 Wayne Stambaugh <stambaughw@verizon.net>
 * Copyright (C) 1992-2011 KiCad Developers, see AUTHORS.txt for contributors.
 *
 * This program is free software; you can redistribute it and/or
@@ -102,23 +101,6 @@ bool SCH_ITEM::operator < ( const SCH_ITEM& aItem ) const
 }
-SCH_ITEM& SCH_ITEM::operator=( const SCH_ITEM& aItem )
-{
-    wxCHECK_MSG( Type() == aItem.Type(), *this,
-                 wxT( "Cannot assign object type " ) + aItem.GetClass() + wxT( " to type " ) +
-                 GetClass() );
-    if( &aItem != this )
-    {
-        EDA_ITEM::operator=( aItem );
-        m_Layer = aItem.m_Layer;
-        m_connections = aItem.m_connections;
-    }
-    return *this;
-}
 void SCH_ITEM::doPlot( PLOTTER* aPlotter )
 {
    wxFAIL_MSG( wxT( "doPlot() method not implemented for class " ) + GetClass() );

--- a/eeschema/block.cpp
+++ b/eeschema/block.cpp
@@ -559,8 +559,7 @@ void SCH_EDIT_FRAME::PasteListOfItems( wxDC* DC )
        SetSchItemParent( Struct, GetScreen() );
        Struct->Draw( m_canvas, DC, wxPoint( 0, 0 ), GR_DEFAULT_DRAWMODE );
-        Struct->SetNext( GetScreen()->GetDrawItems() );
+        GetScreen()->Append( Struct );
-        GetScreen()->SetDrawItems( Struct );
    }
    SaveCopyInUndoList( picklist, UR_NEW );

--- a/eeschema/bus-wire-junction.cpp
+++ b/eeschema/bus-wire-junction.cpp
@@ -2,7 +2,6 @@
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2004 Jean-Pierre Charras, jaen-pierre.charras@gipsa-lab.inpg.com
- * Copyright (C) 2008-2011 Wayne Stambaugh <stambaughw@verizon.net>
 * Copyright (C) 2004-2011 KiCad Developers, see change_log.txt for contributors.
 *
 * This program is free software; you can redistribute it and/or
@@ -51,8 +50,10 @@
 static void AbortCreateNewLine( EDA_DRAW_PANEL* Panel, wxDC* DC );
 static void ComputeBreakPoint( SCH_LINE* segment, const wxPoint& new_pos );
-SCH_ITEM* s_OldWiresList;
+static DLIST< SCH_ITEM > s_wires;
-wxPoint   s_ConnexionStartPoint;
+static DLIST< SCH_ITEM > s_oldWires;
+static wxPoint s_startPoint;
 /**
@@ -61,19 +62,17 @@ wxPoint   s_ConnexionStartPoint;
 static void DrawSegment( EDA_DRAW_PANEL* aPanel, wxDC* aDC, const wxPoint& aPosition,
                         bool aErase )
 {
-    SCH_LINE* CurrentLine = (SCH_LINE*) aPanel->GetScreen()->GetCurItem();
    SCH_LINE* segment;
    int color;
-    if( CurrentLine == NULL )
+    if( s_wires.GetCount() == 0 )
        return;
-    color = ReturnLayerColor( CurrentLine->GetLayer() ) ^ HIGHLIGHT_FLAG;
+    segment = (SCH_LINE*) s_wires.begin();
+    color = ReturnLayerColor( segment->GetLayer() ) ^ HIGHLIGHT_FLAG;
    if( aErase )
    {
-        segment = CurrentLine;
        while( segment )
        {
            if( !segment->IsNull() )  // Redraw if segment length != 0
@@ -86,11 +85,11 @@ static void DrawSegment( EDA_DRAW_PANEL* aPanel, wxDC* aDC, const wxPoint& aPosi
    wxPoint endpos = aPanel->GetScreen()->GetCrossHairPosition();
    if( g_HVLines ) /* Coerce the line to vertical or horizontal one: */
-        ComputeBreakPoint( CurrentLine, endpos );
+        ComputeBreakPoint( (SCH_LINE*) s_wires.GetLast()->Back(), endpos );
    else
-        CurrentLine->SetEndPoint( endpos );
+        ( (SCH_LINE*) s_wires.GetLast() )->SetEndPoint( endpos );
-    segment = CurrentLine;
+    segment = (SCH_LINE*) s_wires.begin();
    while( segment )
    {
@@ -104,259 +103,195 @@ static void DrawSegment( EDA_DRAW_PANEL* aPanel, wxDC* aDC, const wxPoint& aPosi
 void SCH_EDIT_FRAME::BeginSegment( wxDC* DC, int type )
 {
-    SCH_LINE* oldsegment, * newsegment, * nextsegment;
+    SCH_LINE* segment;
+    SCH_LINE* nextSegment;
    wxPoint   cursorpos = GetScreen()->GetCrossHairPosition();
-    if( GetScreen()->GetCurItem() && (GetScreen()->GetCurItem()->GetFlags() == 0) )
+    segment = (SCH_LINE*) GetScreen()->GetCurItem();
-        GetScreen()->SetCurItem( NULL );
-    if( GetScreen()->GetCurItem() )
-    {
-        switch( GetScreen()->GetCurItem()->Type() )
-        {
-        case SCH_LINE_T:
-        case SCH_POLYLINE_T:
-            break;
-        default:
-            return;
-        }
-    }
-    oldsegment = newsegment = (SCH_LINE*) GetScreen()->GetCurItem();
-    if( !newsegment )  /* first point : Create first wire or bus */
+    if( !segment )  /* first point : Create first wire or bus */
    {
-        s_ConnexionStartPoint = cursorpos;
+        s_startPoint = cursorpos;
-        s_OldWiresList = GetScreen()->ExtractWires( true );
+        GetScreen()->ExtractWires( s_oldWires, true );
        GetScreen()->SchematicCleanUp( m_canvas );
        switch( type )
        {
        default:
-            newsegment = new SCH_LINE( cursorpos, LAYER_NOTES );
+            segment = new SCH_LINE( cursorpos, LAYER_NOTES );
            break;
        case LAYER_WIRE:
-            newsegment = new SCH_LINE( cursorpos, LAYER_WIRE );
+            segment = new SCH_LINE( cursorpos, LAYER_WIRE );
            /* A junction will be created later, when we'll know the
             * segment end position, and if the junction is really needed */
            break;
        case LAYER_BUS:
-            newsegment = new SCH_LINE( cursorpos, LAYER_BUS );
+            segment = new SCH_LINE( cursorpos, LAYER_BUS );
            break;
        }
-        newsegment->SetFlags( IS_NEW );
+        segment->SetFlags( IS_NEW );
+        s_wires.PushBack( segment );
+        GetScreen()->SetCurItem( segment );
-        if( g_HVLines ) // We need 2 segments to go from a given start pin to an end point
+        // We need 2 segments to go from a given start pin to an end point when the horizontal
+        // and vertical lines only switch is on.
+        if( g_HVLines )
        {
-            nextsegment = new SCH_LINE( *newsegment );
+            nextSegment = new SCH_LINE( *segment );
-            nextsegment->SetFlags( IS_NEW );
+            nextSegment->SetFlags( IS_NEW );
-            newsegment->SetNext( nextsegment );
+            s_wires.PushBack( nextSegment );
-            nextsegment->SetBack( newsegment );
+            GetScreen()->SetCurItem( nextSegment );
        }
-        GetScreen()->SetCurItem( newsegment );
        m_canvas->SetMouseCapture( DrawSegment, AbortCreateNewLine );
        m_itemToRepeat = NULL;
    }
    else    // A segment is in progress: terminates the current segment and add a new segment.
    {
-        nextsegment = oldsegment->Next();
+        SCH_LINE* prevSegment = (SCH_LINE*) segment->Back();
+        wxLogDebug( wxT( "Adding new segment after " ) + segment->GetSelectMenuText() );
        if( !g_HVLines )
        {
-            // if only one segment is needed and it has length = 0, do not create a new one.
+            // If only one segment is needed and it has a zero length, do not create a new one.
-            if( oldsegment->IsNull() )
+            if( segment->IsNull() )
                return;
        }
        else
        {
-            /* if we want 2 segment and the last two have len = 0, do not
+            wxCHECK_RET( prevSegment != NULL, wxT( "Failed to create second line segment." ) );
-             * create a new one */
-            if( oldsegment->IsNull() && nextsegment && nextsegment->IsNull() )
+            // If two segments are required and they both have zero length, do not
+            // create a new one.
+            if( prevSegment && prevSegment->IsNull() && segment->IsNull() )
                return;
        }
        m_canvas->CallMouseCapture( DC, wxDefaultPosition, false );
-        /* Creates the new segment, or terminates the command
+        // Terminate the command if the end point is on a pin, junction, or another wire or bus.
-         * if the end point is on a pin, junction or an other wire or bus */
+        if( GetScreen()->IsTerminalPoint( cursorpos, segment->GetLayer() ) )
-        if( GetScreen()->IsTerminalPoint( cursorpos, oldsegment->GetLayer() ) )
        {
            EndSegment( DC );
            return;
        }
-        oldsegment->SetNext( GetScreen()->GetDrawItems() );
+        // Create a new segment, and chain it after the current new segment.
-        GetScreen()->SetDrawItems( oldsegment );
+        nextSegment = new SCH_LINE( *segment );
-        m_canvas->CrossHairOff( DC );     // Erase schematic cursor
+        nextSegment->SetStartPoint( cursorpos );
-        oldsegment->Draw( m_canvas, DC, wxPoint( 0, 0 ), GR_DEFAULT_DRAWMODE );
+        s_wires.PushBack( nextSegment );
-        m_canvas->CrossHairOn( DC );      // Display schematic cursor
-        /* Create a new segment, and chain it after the current new segment */
+        segment->SetEndPoint( cursorpos );
-        if( nextsegment )
+        segment->ClearFlags( IS_NEW );
-        {
+        segment->SetFlags( SELECTED );
-            newsegment = new SCH_LINE( *nextsegment );
+        nextSegment->SetFlags( IS_NEW );
-            nextsegment->SetStartPoint( newsegment->GetEndPoint() );
+        GetScreen()->SetCurItem( nextSegment );
-            nextsegment->SetNext( NULL );
-            nextsegment->SetBack( newsegment );
-            newsegment->SetNext( nextsegment );
-            newsegment->SetBack( NULL );
-        }
-        else
-        {
-            newsegment = new SCH_LINE( *oldsegment );
-            newsegment->SetStartPoint( oldsegment->GetEndPoint() );
-        }
-        newsegment->SetEndPoint( cursorpos );
-        oldsegment->ClearFlags( IS_NEW );
-        oldsegment->SetFlags( SELECTED );
-        newsegment->SetFlags( IS_NEW );
-        GetScreen()->SetCurItem( newsegment );
        m_canvas->CallMouseCapture( DC, wxDefaultPosition, false );
-        /* This is the first segment: Now we know the start segment position.
-         * Create a junction if needed. Note: a junction can be needed later,
-         * if the new segment is merged (after a cleanup) with an older one
-         * (tested when the connection will be finished)*/
-        if( oldsegment->GetStartPoint() == s_ConnexionStartPoint )
-        {
-            if( GetScreen()->IsJunctionNeeded( s_ConnexionStartPoint ) )
-                AddJunction( DC, s_ConnexionStartPoint );
-        }
    }
 }
 void SCH_EDIT_FRAME::EndSegment( wxDC* DC )
 {
-    SCH_LINE* firstsegment = (SCH_LINE*) GetScreen()->GetCurItem();
+    SCH_SCREEN* screen = GetScreen();
-    SCH_LINE* lastsegment = firstsegment;
+    SCH_LINE* segment = (SCH_LINE*) screen->GetCurItem();
-    SCH_LINE* segment;
-    if( firstsegment == NULL )
-        return;
-    if( !firstsegment->IsNew() )
+    if( segment == NULL || segment->Type() != SCH_LINE_T || !segment->IsNew() )
        return;
-    /* Delete Null segments and Put line it in Drawlist */
+    // Delete zero length segments and clear item flags.
-    lastsegment = firstsegment;
+    SCH_ITEM* item = s_wires.begin();
-    while( lastsegment )
+    while( item )
    {
-        SCH_LINE* nextsegment = lastsegment->Next();
+        item->ClearFlags();
-        if( lastsegment->IsNull() )
+        wxCHECK_RET( item->Type() == SCH_LINE_T, wxT( "Unexpected object type in wire list." ) );
-        {
-            SCH_LINE* previous_segment = lastsegment->Back();
-            if( firstsegment == lastsegment )
+        segment = (SCH_LINE*) item;
-                firstsegment = nextsegment;
-            if( nextsegment )
+        if( segment->IsNull() )
-                nextsegment->SetBack( NULL );
+        {
+            wxLogDebug( wxT( "Removing null segment: " ) + segment->GetSelectMenuText() );
+            SCH_ITEM* previousSegment = item->Back();
-            if( previous_segment )
+            delete s_wires.Remove( item );
-                previous_segment->SetNext( nextsegment );
-            delete lastsegment;
+            if( previousSegment == NULL )
+                item = s_wires.begin();
+            else
+                item = previousSegment;
        }
-        lastsegment = nextsegment;
+        item = item->Next();
    }
-    /* put the segment list to the main linked list */
+    if( s_wires.GetCount() == 0 )
-    segment = lastsegment = firstsegment;
+        return;
-    while( segment )
-    {
-        lastsegment = segment;
-        segment     = segment->Next();
-        lastsegment->SetNext( GetScreen()->GetDrawItems() );
-        GetScreen()->SetDrawItems( lastsegment );
-    }
+    // Get the last non-null wire.
+    m_itemToRepeat = segment = (SCH_LINE*) s_wires.GetLast();
+    screen->SetCurItem( NULL );
    m_canvas->EndMouseCapture( -1, -1, wxEmptyString, false );
-    GetScreen()->SetCurItem( NULL );
-    wxPoint end_point, alt_end_point;
+    DLIST< SCH_ITEM > tmp;
-    /* A junction can be needed to connect the last segment
+    for( item = s_wires.begin();  item != NULL;  item = item->Next() )
-     *  usually to m_end coordinate.
+        tmp.PushBack( (SCH_ITEM*) item->Clone() );
-     *  But if the last segment is removed by a cleanup, because of redundancy,
-     * a junction can be needed to connect the previous segment m_end
-     * coordinate with is also the lastsegment->m_start coordinate */
-    if( lastsegment )
-    {
-        end_point     = lastsegment->GetEndPoint();
-        alt_end_point = lastsegment->GetStartPoint();
-    }
-    GetScreen()->SchematicCleanUp( m_canvas );
+    // Temporarily add the new segments to the schematic item list to test if any
+    // junctions are required.
+    screen->Append( tmp );
-    /* clear flags and find last segment entered, for repeat function */
+    // Correct and remove segments that need merged.
-    segment = (SCH_LINE*) GetScreen()->GetDrawItems();
+    screen->SchematicCleanUp( m_canvas, DC );
-    while( segment )
+    // A junction may be needed to connect the last segment.  If the last segment was
-    {
+    // removed by a cleanup, a junction may be needed to connect the segment's end point
-        if( segment->GetFlags() )
+    // which is also the same as the previous segment's start point.
-        {
+    if( screen->IsJunctionNeeded( segment->GetEndPoint() ) )
-            if( !m_itemToRepeat )
+        s_wires.Append( AddJunction( DC, segment->GetEndPoint() ) );
-                m_itemToRepeat = segment;
+    else if( screen->IsJunctionNeeded( segment->GetStartPoint() ) )
-        }
+        s_wires.Append( AddJunction( DC, segment->GetStartPoint() ) );
-        segment->ClearFlags();
+    // Automatically place a junction on the start point if necessary because the cleanup
-        segment = segment->Next();
+    // can suppress intermediate points by merging wire segments.
-    }
+    if( screen->IsJunctionNeeded( s_startPoint ) )
+        s_wires.Append( AddJunction( DC, s_startPoint ) );
-    // Automatic place of a junction on the end point, if needed
+    // Make a copy of the original wires, buses, and junctions.
-    if( lastsegment )
+    for( item = s_oldWires.begin();  item != NULL;  item = item->Next() )
-    {
+        tmp.PushBack( (SCH_ITEM*) item->Clone() );
-        if( GetScreen()->IsJunctionNeeded( end_point ) )
-            AddJunction( DC, end_point );
-        else if( GetScreen()->IsJunctionNeeded( alt_end_point ) )
-            AddJunction( DC, alt_end_point );
-    }
-    /* Automatic place of a junction on the start point if necessary because
+    // Restore the old wires.
-     * the cleanup can suppress intermediate points by merging wire segments */
+    if( tmp.GetCount() != 0 )
-    if( GetScreen()->IsJunctionNeeded( s_ConnexionStartPoint ) )
+        screen->ReplaceWires( tmp );
-        AddJunction( DC, s_ConnexionStartPoint );
-    GetScreen()->TestDanglingEnds( m_canvas, DC );
+    // Now add the new wires and any required junctions to the schematic item list.
+    screen->Append( s_wires );
-    /* Redraw wires and junctions which can be changed by TestDanglingEnds() */
+    screen->SchematicCleanUp( m_canvas, DC );
-    m_canvas->CrossHairOff( DC );   // Erase schematic cursor
-    EDA_ITEM* item = GetScreen()->GetDrawItems();
-    while( item )
+    // Put the snap shot of the previous wire, buses, and junctions in the undo/redo list.
-    {
+    PICKED_ITEMS_LIST oldItems;
-        switch( item->Type() )
-        {
-        case SCH_JUNCTION_T:
-        case SCH_LINE_T:
-            m_canvas->RefreshDrawingRect( item->GetBoundingBox() );
-            break;
-        default:
+    oldItems.m_Status = UR_WIRE_IMAGE;
-            break;
-        }
-        item = item->Next();
+    while( s_oldWires.GetCount() != 0 )
+    {
+        ITEM_PICKER picker = ITEM_PICKER( s_oldWires.PopFront(), UR_WIRE_IMAGE );
+        oldItems.PushItem( picker );
    }
-    m_canvas->CrossHairOn( DC );    // Display schematic cursor
+    SaveCopyInUndoList( oldItems, UR_WIRE_IMAGE );
-    SaveCopyInUndoList( s_OldWiresList, UR_WIRE_IMAGE );
+    OnModify();
-    s_OldWiresList = NULL;
-    OnModify( );
 }
@@ -364,45 +299,53 @@ void SCH_EDIT_FRAME::EndSegment( wxDC* DC )
 * Function ComputeBreakPoint
 * computes the middle coordinate for 2 segments from the start point to \a aPosition
 * with the segments kept in the horizontal or vertical axis only.
+ *
+ * @param aSegment A pointer to a #SCH_LINE object containing the first line break point
+ *                 to compute.
+ * @param aPosition A reference to a wxPoint object containing the coordinates of the
+ *                  position used to calculate the line break point.
 */
 static void ComputeBreakPoint( SCH_LINE* aSegment, const wxPoint& aPosition )
 {
-    SCH_LINE* nextsegment     = aSegment->Next();
+    wxCHECK_RET( aSegment != NULL, wxT( "Cannot compute break point of NULL line segment." ) );
-    wxPoint   middle_position = aPosition;
+    SCH_LINE* nextSegment = aSegment->Next();
+    wxPoint midPoint = aPosition;
+    wxCHECK_RET( nextSegment != NULL,
+                 wxT( "Cannot compute break point of NULL second line segment." ) );
-    if( nextsegment == NULL )
-        return;
 #if 0
-    if( ABS( middle_position.x - aSegment->GetStartPoint().x ) <
+    if( ABS( midPoint.x - aSegment->GetStartPoint().x ) <
-        ABS( middle_position.y - aSegment->GetStartPoint().y ) )
+        ABS( midPoint.y - aSegment->GetStartPoint().y ) )
-        middle_position.x = aSegment->GetStartPoint().x;
+        midPoint.x = aSegment->GetStartPoint().x;
    else
-        middle_position.y = aSegment->GetStartPoint().y;
+        midPoint.y = aSegment->GetStartPoint().y;
 #else
    int iDx = aSegment->GetEndPoint().x - aSegment->GetStartPoint().x;
    int iDy = aSegment->GetEndPoint().y - aSegment->GetStartPoint().y;
    if( iDy != 0 )         // keep the first segment orientation (currently horizontal)
    {
-        middle_position.x = aSegment->GetStartPoint().x;
+        midPoint.x = aSegment->GetStartPoint().x;
    }
    else if( iDx != 0 )    // keep the first segment orientation (currently vertical)
    {
-        middle_position.y = aSegment->GetStartPoint().y;
+        midPoint.y = aSegment->GetStartPoint().y;
    }
    else
    {
-        if( ABS( middle_position.x - aSegment->GetStartPoint().x ) <
+        if( ABS( midPoint.x - aSegment->GetStartPoint().x ) <
-            ABS( middle_position.y - aSegment->GetStartPoint().y ) )
+            ABS( midPoint.y - aSegment->GetStartPoint().y ) )
-            middle_position.x = aSegment->GetStartPoint().x;
+            midPoint.x = aSegment->GetStartPoint().x;
        else
-            middle_position.y = aSegment->GetStartPoint().y;
+            midPoint.y = aSegment->GetStartPoint().y;
    }
 #endif
-    aSegment->SetEndPoint( middle_position );
+    aSegment->SetEndPoint( midPoint );
-    nextsegment->SetStartPoint( middle_position );
+    nextSegment->SetStartPoint( midPoint );
-    nextsegment->SetEndPoint( aPosition );
+    nextSegment->SetEndPoint( aPosition );
 }
@@ -443,7 +386,7 @@ void SCH_EDIT_FRAME::DeleteCurrentSegment( wxDC* DC )
        DrawSegment( m_canvas, DC, wxDefaultPosition, false );
    }
-    screen->RemoveFromDrawList( screen->GetCurItem() );
+    screen->Remove( screen->GetCurItem() );
    m_canvas->SetMouseCaptureCallback( NULL );
    screen->SetCurItem( NULL );
 }
@@ -460,12 +403,12 @@ SCH_JUNCTION* SCH_EDIT_FRAME::AddJunction( wxDC* aDC, const wxPoint& aPosition,
    junction->Draw( m_canvas, aDC, wxPoint( 0, 0 ), GR_DEFAULT_DRAWMODE );
    m_canvas->CrossHairOn( aDC );      // Display schematic cursor
-    junction->SetNext( GetScreen()->GetDrawItems() );
-    GetScreen()->SetDrawItems( junction );
-    OnModify();
    if( aPutInUndoList )
+    {
+        GetScreen()->Append( junction );
        SaveCopyInUndoList( junction, UR_NEW );
+        OnModify();
+    }
    return junction;
 }
@@ -482,8 +425,7 @@ SCH_NO_CONNECT* SCH_EDIT_FRAME::AddNoConnect( wxDC* aDC, const wxPoint& aPositio
    NewNoConnect->Draw( m_canvas, aDC, wxPoint( 0, 0 ), GR_DEFAULT_DRAWMODE );
    m_canvas->CrossHairOn( aDC );      // Display schematic cursor
-    NewNoConnect->SetNext( GetScreen()->GetDrawItems() );
+    GetScreen()->Append( NewNoConnect );
-    GetScreen()->SetDrawItems( NewNoConnect );
    OnModify();
    SaveCopyInUndoList( NewNoConnect, UR_NEW );
    return NewNoConnect;
@@ -498,9 +440,9 @@ static void AbortCreateNewLine( EDA_DRAW_PANEL* Panel, wxDC* DC )
    if( screen->GetCurItem() )
    {
-        screen->RemoveFromDrawList( (SCH_ITEM*) screen->GetCurItem() );
+        s_wires.DeleteAll();
+        s_oldWires.DeleteAll();
        screen->SetCurItem( NULL );
-        screen->ReplaceWires( s_OldWiresList );
        Panel->Refresh();
    }
    else
@@ -540,8 +482,7 @@ void SCH_EDIT_FRAME::RepeatDrawItem( wxDC* DC )
    if( m_itemToRepeat )
    {
-        m_itemToRepeat->SetNext( GetScreen()->GetDrawItems() );
+        GetScreen()->Append( m_itemToRepeat );
-        GetScreen()->SetDrawItems( m_itemToRepeat );
        GetScreen()->TestDanglingEnds();
        m_itemToRepeat->Draw( m_canvas, DC, wxPoint( 0, 0 ), GR_DEFAULT_DRAWMODE );
        SaveCopyInUndoList( m_itemToRepeat, UR_NEW );

--- a/eeschema/edit_label.cpp
+++ b/eeschema/edit_label.cpp
@@ -2,7 +2,6 @@
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2004 Jean-Pierre Charras, jaen-pierre.charras@gipsa-lab.inpg.com
- * Copyright (C) 2008-2011 Wayne Stambaugh <stambaughw@verizon.net>
 * Copyright (C) 2004-2011 KiCad Developers, see change_log.txt for contributors.
 *
 * This program is free software; you can redistribute it and/or
@@ -224,9 +223,8 @@ void SCH_EDIT_FRAME::OnConvertTextType( wxCommandEvent& aEvent )
    m_canvas->CrossHairOff( &dc );   // Erase schematic cursor
    text->Draw( m_canvas, &dc, wxPoint( 0, 0 ), g_XorMode );
-    screen->RemoveFromDrawList( text );
+    screen->Remove( text );
-    screen->AddToDrawList( newtext );
+    screen->Append( newtext );
-    GetScreen()->SetCurItem( newtext );
    m_itemToRepeat = NULL;
    OnModify();
    newtext->Draw( m_canvas, &dc, wxPoint( 0, 0 ), GR_DEFAULT_DRAWMODE );

--- a/eeschema/erc.cpp
+++ b/eeschema/erc.cpp
@@ -211,8 +211,7 @@ int TestDuplicateSheetNames( bool aCreateMarker )
                                         ( (SCH_SHEET*) test_item )->GetPosition() );
                        marker->SetMarkerType( MARK_ERC );
                        marker->SetErrorLevel( ERR );
-                        marker->SetNext( screen->GetDrawItems() );
+                        screen->Append( marker );
-                        screen->SetDrawItems( marker );
                    }
                    err_count++;
@@ -242,8 +241,7 @@ void Diagnose( NETLIST_OBJECT* aNetItemRef, NETLIST_OBJECT* aNetItemTst,
    marker->SetMarkerType( MARK_ERC );
    marker->SetErrorLevel( WAR );
    screen = aNetItemRef->m_SheetList.LastScreen();
-    marker->SetNext( screen->GetDrawItems() );
+    screen->Append( marker );
-    screen->SetDrawItems( marker );
    wxString msg;

--- a/eeschema/load_one_schematic_file.cpp
+++ b/eeschema/load_one_schematic_file.cpp
@@ -57,8 +57,6 @@ bool SCH_EDIT_FRAME::LoadOneEEFile( SCH_SCREEN* aScreen, const wxString& aFullFi
 {
    char            Name1[256];
    bool            itemLoaded = false;
-    SCH_ITEM*       Phead;
-    SCH_ITEM*       Pnext;
    SCH_ITEM*       item;
    wxString        MsgDiag;            // Error and log messages
    char*           line;
@@ -228,8 +226,7 @@ again." );
            }
            else
            {
-                item->SetNext( aScreen->GetDrawItems() );
+                aScreen->Append( item );
-                aScreen->SetDrawItems( item );
            }
        }
@@ -240,19 +237,6 @@ again." );
        }
    }
-    /* GetDrawItems() was constructed in reverse order - reverse it back: */
-    Phead = NULL;
-    while( aScreen->GetDrawItems() )
-    {
-        Pnext = aScreen->GetDrawItems();
-        aScreen->SetDrawItems( aScreen->GetDrawItems()->Next() );
-        Pnext->SetNext( Phead );
-        Phead = Pnext;
-    }
-    aScreen->SetDrawItems( Phead );
 #if 0 && defined (DEBUG)
    aScreen->Show( 0, std::cout );
 #endif

--- a/eeschema/operations_on_items_lists.cpp
+++ b/eeschema/operations_on_items_lists.cpp
@@ -126,11 +126,9 @@ void DeleteItemsInList( EDA_DRAW_PANEL* panel, PICKED_ITEMS_LIST& aItemsList )
        }
        else
        {
-            screen->RemoveFromDrawList( item );
+            screen->Remove( item );
            /* Unlink the structure */
-            item->SetNext( 0 );
-            item->SetBack( 0 );
            itemsList.PushItem( itemWrapper );
        }
    }
@@ -160,11 +158,7 @@ void SCH_EDIT_FRAME::DeleteItem( SCH_ITEM* aItem )
    }
    else
    {
-        screen->RemoveFromDrawList( aItem );
+        screen->Remove( aItem );
-        aItem->SetNext( NULL );
-        aItem->SetBack( NULL );  // Only one struct -> no link
        SaveCopyInUndoList( aItem, UR_DELETED );
        m_canvas->RefreshDrawingRect( aItem->GetBoundingBox() );
    }
@@ -220,8 +214,7 @@ void DuplicateItemsInList( SCH_SCREEN* screen, PICKED_ITEMS_LIST& aItemsList,
            }
            SetSchItemParent( newitem, screen );
-            newitem->SetNext( screen->GetDrawItems() );
+            screen->Append( newitem );
-            screen->SetDrawItems( newitem );
        }
    }

--- a/eeschema/sch_bus_entry.cpp
+++ b/eeschema/sch_bus_entry.cpp
@@ -2,7 +2,6 @@
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2004 Jean-Pierre Charras, jaen-pierre.charras@gipsa-lab.inpg.com
- * Copyright (C) 2008-2011 Wayne Stambaugh <stambaughw@verizon.net>
 * Copyright (C) 2004-2011 KiCad Developers, see change_log.txt for contributors.
 *
 * This program is free software; you can redistribute it and/or

--- a/eeschema/sch_bus_entry.h
+++ b/eeschema/sch_bus_entry.h
@@ -2,7 +2,6 @@
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2004 Jean-Pierre Charras, jaen-pierre.charras@gipsa-lab.inpg.com
- * Copyright (C) 2008-2011 Wayne Stambaugh <stambaughw@verizon.net>
 * Copyright (C) 2004-2011 KiCad Developers, see change_log.txt for contributors.
 *
 * This program is free software; you can redistribute it and/or

--- a/eeschema/sch_component.cpp
+++ b/eeschema/sch_component.cpp
@@ -2,7 +2,6 @@
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2009 Jean-Pierre Charras, jaen-pierre.charras@gipsa-lab.inpg.com
- * Copyright (C) 2011 Wayne Stambaugh <stambaughw@verizon.net>
 * Copyright (C) 1992-2011 KiCad Developers, see AUTHORS.txt for contributors.
 *
 * This program is free software; you can redistribute it and/or

--- a/eeschema/sch_component.h
+++ b/eeschema/sch_component.h
@@ -2,7 +2,6 @@
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2009 Jean-Pierre Charras, jaen-pierre.charras@gipsa-lab.inpg.com
- * Copyright (C) 2011 Wayne Stambaugh <stambaughw@verizon.net>
 * Copyright (C) 1992-2011 KiCad Developers, see AUTHORS.txt for contributors.
 *
 * This program is free software; you can redistribute it and/or

--- a/eeschema/sch_field.cpp
+++ b/eeschema/sch_field.cpp
@@ -2,7 +2,6 @@
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2004 Jean-Pierre Charras, jaen-pierre.charras@gipsa-lab.inpg.com
- * Copyright (C) 2008-2011 Wayne Stambaugh <stambaughw@verizon.net>
 * Copyright (C) 2004-2011 KiCad Developers, see change_log.txt for contributors.
 *
 * This program is free software; you can redistribute it and/or

--- a/eeschema/sch_field.h
+++ b/eeschema/sch_field.h
@@ -2,7 +2,6 @@
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2004 Jean-Pierre Charras, jaen-pierre.charras@gipsa-lab.inpg.com
- * Copyright (C) 2008-2011 Wayne Stambaugh <stambaughw@verizon.net>
 * Copyright (C) 2004-2011 KiCad Developers, see change_log.txt for contributors.
 *
 * This program is free software; you can redistribute it and/or

--- a/eeschema/sch_junction.cpp
+++ b/eeschema/sch_junction.cpp
@@ -2,7 +2,6 @@
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2009 Jean-Pierre Charras, jaen-pierre.charras@gipsa-lab.inpg.com
- * Copyright (C) 2011 Wayne Stambaugh <stambaughw@verizon.net>
 * Copyright (C) 1992-2011 KiCad Developers, see AUTHORS.txt for contributors.
 *
 * This program is free software; you can redistribute it and/or

--- a/eeschema/sch_junction.h
+++ b/eeschema/sch_junction.h
@@ -2,7 +2,6 @@
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2009 Jean-Pierre Charras, jaen-pierre.charras@gipsa-lab.inpg.com
- * Copyright (C) 2011 Wayne Stambaugh <stambaughw@verizon.net>
 * Copyright (C) 1992-2011 KiCad Developers, see AUTHORS.txt for contributors.
 *
 * This program is free software; you can redistribute it and/or

--- a/eeschema/sch_line.cpp
+++ b/eeschema/sch_line.cpp
@@ -2,7 +2,6 @@
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2009 Jean-Pierre Charras, jaen-pierre.charras@gipsa-lab.inpg.com
- * Copyright (C) 2011 Wayne Stambaugh <stambaughw@verizon.net>
 * Copyright (C) 1992-2011 KiCad Developers, see AUTHORS.txt for contributors.
 *
 * This program is free software; you can redistribute it and/or

--- a/eeschema/sch_line.h
+++ b/eeschema/sch_line.h
@@ -2,7 +2,6 @@
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2009 Jean-Pierre Charras, jaen-pierre.charras@gipsa-lab.inpg.com
- * Copyright (C) 2011 Wayne Stambaugh <stambaughw@verizon.net>
 * Copyright (C) 1992-2011 KiCad Developers, see AUTHORS.txt for contributors.
 *
 * This program is free software; you can redistribute it and/or

--- a/eeschema/sch_marker.h
+++ b/eeschema/sch_marker.h
@@ -2,7 +2,6 @@
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2004 Jean-Pierre Charras, jaen-pierre.charras@gipsa-lab.inpg.com
- * Copyright (C) 2008-2011 Wayne Stambaugh <stambaughw@verizon.net>
 * Copyright (C) 2004-2011 KiCad Developers, see change_log.txt for contributors.
 *
 * This program is free software; you can redistribute it and/or

--- a/eeschema/sch_no_connect.cpp
+++ b/eeschema/sch_no_connect.cpp
@@ -2,7 +2,6 @@
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2009 Jean-Pierre Charras, jaen-pierre.charras@gipsa-lab.inpg.com
- * Copyright (C) 2011 Wayne Stambaugh <stambaughw@verizon.net>
 * Copyright (C) 1992-2011 KiCad Developers, see AUTHORS.txt for contributors.
 *
 * This program is free software; you can redistribute it and/or

--- a/eeschema/sch_no_connect.h
+++ b/eeschema/sch_no_connect.h
@@ -2,7 +2,6 @@
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2009 Jean-Pierre Charras, jaen-pierre.charras@gipsa-lab.inpg.com
- * Copyright (C) 2011 Wayne Stambaugh <stambaughw@verizon.net>
 * Copyright (C) 1992-2011 KiCad Developers, see AUTHORS.txt for contributors.
 *
 * This program is free software; you can redistribute it and/or

--- a/eeschema/sch_polyline.cpp
+++ b/eeschema/sch_polyline.cpp
@@ -2,7 +2,6 @@
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2004 Jean-Pierre Charras, jaen-pierre.charras@gipsa-lab.inpg.com
- * Copyright (C) 2008-2011 Wayne Stambaugh <stambaughw@verizon.net>
 * Copyright (C) 2004-2011 KiCad Developers, see change_log.txt for contributors.
 *
 * This program is free software; you can redistribute it and/or

--- a/eeschema/sch_polyline.h
+++ b/eeschema/sch_polyline.h
@@ -2,7 +2,6 @@
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2004 Jean-Pierre Charras, jaen-pierre.charras@gipsa-lab.inpg.com
- * Copyright (C) 2008-2011 Wayne Stambaugh <stambaughw@verizon.net>
 * Copyright (C) 2004-2011 KiCad Developers, see change_log.txt for contributors.
 *
 * This program is free software; you can redistribute it and/or
@@ -37,7 +36,7 @@
 class SCH_POLYLINE : public SCH_ITEM
 {
-    int m_width;                            /* Thickness */
+    int m_width;                        // Thickness
    std::vector<wxPoint> m_points;      // list of points (>= 2)
 public:

--- a/eeschema/sch_screen.cpp
+++ b/eeschema/sch_screen.cpp
@@ -2,7 +2,6 @@
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2009 Jean-Pierre Charras, jaen-pierre.charras@gipsa-lab.inpg.com
- * Copyright (C) 2010 Wayne Stambaugh <stambaughw@verizon.net>
 * Copyright (C) 1992-2011 KiCad Developers, see AUTHORS.txt for contributors.
 *
 * This program is free software; you can redistribute it and/or
@@ -103,8 +102,6 @@ SCH_SCREEN::SCH_SCREEN() :
 {
    size_t i;
-    SetDrawItems( NULL );               // Schematic items list
    SetZoom( 32 );
    for( i = 0; i < SCHEMATIC_ZOOM_LIST_CNT; i++ )
@@ -158,46 +155,19 @@ void SCH_SCREEN::Clear()
 void SCH_SCREEN::FreeDrawList()
 {
-    SCH_ITEM* item;
+    m_drawList.DeleteAll();
-    while( GetDrawItems() != NULL )
-    {
-        item = GetDrawItems();
-        SetDrawItems( GetDrawItems()->Next() );
-        SAFE_DELETE( item );
-    }
-    SetDrawItems( NULL );
 }
-void SCH_SCREEN::RemoveFromDrawList( SCH_ITEM* aItem )
+void SCH_SCREEN::Remove( SCH_ITEM* aItem )
 {
-    if( aItem == GetDrawItems() )
+    m_drawList.Remove( aItem );
-    {
-        SetDrawItems( GetDrawItems()->Next() );
-    }
-    else
-    {
-        EDA_ITEM* DrawList = GetDrawItems();
-        while( DrawList && DrawList->Next() )
-        {
-            if( DrawList->Next() == aItem )
-            {
-                DrawList->SetNext( DrawList->Next()->Next() );
-                break;
-            }
-            DrawList = DrawList->Next();
-        }
-    }
 }
 void SCH_SCREEN::DeleteItem( SCH_ITEM* aItem )
 {
-    wxCHECK_RET( aItem != NULL, wxT( "Cannot delete invaled item from screen." ) );
+    wxCHECK_RET( aItem != NULL, wxT( "Cannot delete invalid item from screen." ) );
    SetModify();
@@ -213,34 +183,14 @@ void SCH_SCREEN::DeleteItem( SCH_ITEM* aItem )
    }
    else
    {
-        if( aItem == GetDrawItems() )
+        delete m_drawList.Remove( aItem );
-        {
-            SetDrawItems( aItem->Next() );
-            SAFE_DELETE( aItem );
-        }
-        else
-        {
-            SCH_ITEM* itemList = GetDrawItems();
-            while( itemList && itemList->Next() )
-            {
-                if( itemList->Next() == aItem )
-                {
-                    itemList->SetNext( aItem->Next() );
-                    SAFE_DELETE( aItem );
-                    return;
-                }
-                itemList = itemList->Next();
-            }
-        }
    }
 }
 bool SCH_SCREEN::CheckIfOnDrawList( SCH_ITEM* aItem )
 {
-    SCH_ITEM* itemList = GetDrawItems();
+    SCH_ITEM* itemList = m_drawList.begin();
    while( itemList )
    {
@@ -254,19 +204,9 @@ bool SCH_SCREEN::CheckIfOnDrawList( SCH_ITEM* aItem )
 }
-void SCH_SCREEN::AddToDrawList( SCH_ITEM* aItem )
-{
-    if( aItem == NULL )
-        return;
-    aItem->SetNext( GetDrawItems() );
-    SetDrawItems( aItem );
-}
 SCH_ITEM* SCH_SCREEN::GetItem( const wxPoint& aPosition, int aAccuracy, KICAD_T aType ) const
 {
-    for( SCH_ITEM* item = GetDrawItems(); item != NULL; item = item->Next() )
+    for( SCH_ITEM* item = m_drawList.begin(); item != NULL; item = item->Next() )
    {
        if( item->HitTest( aPosition, aAccuracy ) && (aType == NOT_USED) )
            return item;
@@ -302,11 +242,12 @@ SCH_ITEM* SCH_SCREEN::GetItem( const wxPoint& aPosition, int aAccuracy, KICAD_T
 }
-SCH_ITEM* SCH_SCREEN::ExtractWires( bool CreateCopy )
+void SCH_SCREEN::ExtractWires( DLIST< SCH_ITEM >& aList, bool aCreateCopy )
 {
-    SCH_ITEM* item, * next_item, * new_item, * List = NULL;
+    SCH_ITEM* item;
+    SCH_ITEM* next_item;
-    for( item = GetDrawItems(); item != NULL; item = next_item )
+    for( item = m_drawList.begin(); item != NULL; item = next_item )
    {
        next_item = item->Next();
@@ -314,33 +255,27 @@ SCH_ITEM* SCH_SCREEN::ExtractWires( bool CreateCopy )
        {
        case SCH_JUNCTION_T:
        case SCH_LINE_T:
-            RemoveFromDrawList( item );
+            m_drawList.Remove( item );
-            item->SetNext( List );
+            aList.Append( item );
-            List = item;
+            if( aCreateCopy )
+                m_drawList.Insert( item->Clone(), next_item );
-            if( CreateCopy )
-            {
-                new_item = item->Clone();
-                new_item->SetNext( GetDrawItems() );
-                SetDrawItems( new_item );
-            }
            break;
        default:
            break;
        }
    }
-    return List;
 }
-void SCH_SCREEN::ReplaceWires( SCH_ITEM* aWireList )
+void SCH_SCREEN::ReplaceWires( DLIST< SCH_ITEM >& aWireList )
 {
    SCH_ITEM* item;
    SCH_ITEM* next_item;
-    for( item = GetDrawItems(); item != NULL; item = next_item )
+    for( item = m_drawList.begin(); item != NULL; item = next_item )
    {
        next_item = item->Next();
@@ -348,7 +283,7 @@ void SCH_SCREEN::ReplaceWires( SCH_ITEM* aWireList )
        {
        case SCH_JUNCTION_T:
        case SCH_LINE_T:
-            RemoveFromDrawList( item );
+            Remove( item );
            delete item;
            break;
@@ -357,14 +292,7 @@ void SCH_SCREEN::ReplaceWires( SCH_ITEM* aWireList )
        }
    }
-    while( aWireList )
+    m_drawList.Append( aWireList );
-    {
-        next_item = aWireList->Next();
-        aWireList->SetNext( GetDrawItems() );
-        SetDrawItems( aWireList );
-        aWireList = next_item;
-    }
 }
@@ -373,7 +301,7 @@ void SCH_SCREEN::MarkConnections( SCH_LINE* aSegment )
    wxCHECK_RET( (aSegment != NULL) && (aSegment->Type() == SCH_LINE_T),
                 wxT( "Invalid object pointer." ) );
-    for( SCH_ITEM* item = GetDrawItems(); item != NULL; item = item->Next() )
+    for( SCH_ITEM* item = m_drawList.begin(); item != NULL; item = item->Next() )
    {
        if( item->GetFlags() & CANDIDATE )
            continue;
@@ -498,50 +426,50 @@ bool SCH_SCREEN::IsTerminalPoint( const wxPoint& aPosition, int aLayer )
 bool SCH_SCREEN::SchematicCleanUp( EDA_DRAW_PANEL* aCanvas, wxDC* aDC )
 {
-    SCH_ITEM* DrawList, * TstDrawList;
+    SCH_ITEM* item, * testItem;
-    bool      Modify = false;
+    bool      modified = false;
-    DrawList = GetDrawItems();
+    item = m_drawList.begin();
-    for( ; DrawList != NULL; DrawList = DrawList->Next() )
+    for( ; item != NULL; item = item->Next() )
    {
-        if( DrawList->Type() == SCH_LINE_T )
+        if( item->Type() != SCH_LINE_T )
-        {
+            continue;
-            TstDrawList = DrawList->Next();
-            while( TstDrawList )
+        testItem = item->Next();
+        while( testItem )
+        {
+            if( testItem->Type() == SCH_LINE_T )
            {
-                if( TstDrawList->Type() == SCH_LINE_T )
+                SCH_LINE* line = (SCH_LINE*) item;
+                if( line->MergeOverlap( (SCH_LINE*) testItem ) )
                {
-                    SCH_LINE* line = (SCH_LINE*) DrawList;
+                    // Keep the current flags, because the deleted segment can be flagged.
+                    item->SetFlags( testItem->GetFlags() );
-                    if( line->MergeOverlap( (SCH_LINE*) TstDrawList ) )
+                    DeleteItem( testItem );
-                    {
+                    testItem = m_drawList.begin();
-                        // Keep the current flags, because the deleted segment can be flagged.
+                    modified = true;
-                        DrawList->SetFlags( TstDrawList->GetFlags() );
-                        DeleteItem( TstDrawList );
-                        TstDrawList = GetDrawItems();
-                        Modify = true;
-                    }
-                    else
-                    {
-                        TstDrawList = TstDrawList->Next();
-                    }
                }
                else
                {
-                    TstDrawList = TstDrawList->Next();
+                    testItem = testItem->Next();
                }
            }
+            else
+            {
+                testItem = testItem->Next();
+            }
        }
    }
    TestDanglingEnds( aCanvas, aDC );
-    if( aCanvas && Modify )
+    if( aCanvas && modified )
        aCanvas->Refresh();
-    return Modify;
+    return modified;
 }
@@ -590,7 +518,7 @@ bool SCH_SCREEN::Save( FILE* aFile ) const
        || fprintf( aFile, "$EndDescr\n" ) < 0 )
        return false;
-    for( SCH_ITEM* item = GetDrawItems(); item; item = item->Next() )
+    for( SCH_ITEM* item = m_drawList.begin(); item; item = item->Next() )
    {
        if( !item->Save( aFile ) )
            return false;
@@ -605,7 +533,7 @@ bool SCH_SCREEN::Save( FILE* aFile ) const
 void SCH_SCREEN::Draw( EDA_DRAW_PANEL* aCanvas, wxDC* aDC, int aDrawMode, int aColor )
 {
-    for( SCH_ITEM* item = GetDrawItems(); item != NULL; item = item->Next() )
+    for( SCH_ITEM* item = m_drawList.begin(); item != NULL; item = item->Next() )
    {
        if( item->IsMoving() || item->IsResized() )
            continue;
@@ -621,7 +549,7 @@ void SCH_SCREEN::Draw( EDA_DRAW_PANEL* aCanvas, wxDC* aDC, int aDrawMode, int aC
 void SCH_SCREEN::Plot( PLOTTER* aPlotter )
 {
-    for( SCH_ITEM* item = GetDrawItems();  item;  item = item->Next() )
+    for( SCH_ITEM* item = m_drawList.begin();  item;  item = item->Next() )
    {
        aPlotter->set_current_line_width( item->GetPenSize() );
        item->Plot( aPlotter );
@@ -655,7 +583,7 @@ void SCH_SCREEN::ClearUndoORRedoList( UNDO_REDO_CONTAINER& aList, int aItemCount
 void SCH_SCREEN::ClearDrawingState()
 {
-    for( SCH_ITEM* item = GetDrawItems(); item != NULL; item = item->Next() )
+    for( SCH_ITEM* item = m_drawList.begin(); item != NULL; item = item->Next() )
        item->ClearFlags();
 }
@@ -667,7 +595,7 @@ LIB_PIN* SCH_SCREEN::GetPin( const wxPoint& aPosition, SCH_COMPONENT** aComponen
    SCH_COMPONENT* component = NULL;
    LIB_PIN* pin = NULL;
-    for( item = GetDrawItems(); item != NULL; item = item->Next() )
+    for( item = m_drawList.begin(); item != NULL; item = item->Next() )
    {
        if( item->Type() != SCH_COMPONENT_T )
            continue;
@@ -717,7 +645,7 @@ LIB_PIN* SCH_SCREEN::GetPin( const wxPoint& aPosition, SCH_COMPONENT** aComponen
 SCH_SHEET* SCH_SCREEN::GetSheet( const wxString& aName )
 {
-    for( SCH_ITEM* item = GetDrawItems(); item != NULL; item = item->Next() )
+    for( SCH_ITEM* item = m_drawList.begin(); item != NULL; item = item->Next() )
    {
        if( item->Type() != SCH_SHEET_T )
            continue;
@@ -736,7 +664,7 @@ SCH_SHEET_PIN* SCH_SCREEN::GetSheetLabel( const wxPoint& aPosition )
 {
    SCH_SHEET_PIN* sheetPin = NULL;
-    for( SCH_ITEM* item = GetDrawItems(); item != NULL; item = item->Next() )
+    for( SCH_ITEM* item = m_drawList.begin(); item != NULL; item = item->Next() )
    {
        if( item->Type() != SCH_SHEET_T )
            continue;
@@ -757,7 +685,7 @@ int SCH_SCREEN::CountConnectedItems( const wxPoint& aPos, bool aTestJunctions )
    SCH_ITEM* item;
    int       count = 0;
-    for( item = GetDrawItems(); item != NULL; item = item->Next() )
+    for( item = m_drawList.begin(); item != NULL; item = item->Next() )
    {
        if( item->Type() == SCH_JUNCTION_T  && !aTestJunctions )
            continue;
@@ -772,7 +700,7 @@ int SCH_SCREEN::CountConnectedItems( const wxPoint& aPos, bool aTestJunctions )
 void SCH_SCREEN::ClearAnnotation( SCH_SHEET_PATH* aSheetPath )
 {
-    for( SCH_ITEM* item = GetDrawItems(); item != NULL; item = item->Next() )
+    for( SCH_ITEM* item = m_drawList.begin(); item != NULL; item = item->Next() )
    {
        if( item->Type() == SCH_COMPONENT_T )
        {
@@ -786,7 +714,7 @@ void SCH_SCREEN::ClearAnnotation( SCH_SHEET_PATH* aSheetPath )
 void SCH_SCREEN::GetHierarchicalItems( EDA_ITEMS& aItems )
 {
-    SCH_ITEM* item = GetDrawItems();
+    SCH_ITEM* item = m_drawList.begin();
    while( item )
    {
@@ -869,7 +797,7 @@ void SCH_SCREEN::addConnectedItemsToBlock( const wxPoint& position )
    ITEM_PICKER picker;
    bool addinlist = true;
-    for( item = GetDrawItems(); item != NULL; item = item->Next() )
+    for( item = m_drawList.begin(); item != NULL; item = item->Next() )
    {
        picker.SetItem( item );
@@ -915,7 +843,7 @@ int SCH_SCREEN::UpdatePickList()
    area.SetSize( m_BlockLocate.GetSize() );
    area.Normalize();
-    for( SCH_ITEM* item = GetDrawItems(); item != NULL; item = item->Next() )
+    for( SCH_ITEM* item = m_drawList.begin(); item != NULL; item = item->Next() )
    {
        // An item is picked if its bounding box intersects the reference area.
        if( item->HitTest( area ) )
@@ -935,10 +863,10 @@ bool SCH_SCREEN::TestDanglingEnds( EDA_DRAW_PANEL* aCanvas, wxDC* aDC )
    std::vector< DANGLING_END_ITEM > endPoints;
    bool hasDanglingEnds = false;
-    for( item = GetDrawItems(); item != NULL; item = item->Next() )
+    for( item = m_drawList.begin(); item != NULL; item = item->Next() )
        item->GetEndPoints( endPoints );
-    for( item = GetDrawItems(); item; item = item->Next() )
+    for( item = m_drawList.begin(); item; item = item->Next() )
    {
        if( item->IsDanglingStateChanged( endPoints ) && ( aCanvas != NULL ) && ( aDC != NULL ) )
        {
@@ -960,7 +888,7 @@ bool SCH_SCREEN::BreakSegment( const wxPoint& aPoint )
    SCH_LINE* newSegment;
    bool brokenSegments = false;
-    for( SCH_ITEM* item = GetDrawItems(); item != NULL; item = item->Next() )
+    for( SCH_ITEM* item = m_drawList.begin(); item != NULL; item = item->Next() )
    {
        if( (item->Type() != SCH_LINE_T) || (item->GetLayer() == LAYER_NOTES) )
            continue;
@@ -974,8 +902,7 @@ bool SCH_SCREEN::BreakSegment( const wxPoint& aPoint )
        newSegment = new SCH_LINE( *segment );
        newSegment->SetStartPoint( aPoint );
        segment->SetEndPoint( aPoint );
-        newSegment->SetNext( segment->Next() );
+        m_drawList.Insert( newSegment, segment->Next() );
-        segment->SetNext( newSegment );
        item = newSegment;
        brokenSegments = true;
    }
@@ -988,7 +915,7 @@ bool SCH_SCREEN::BreakSegmentsOnJunctions()
 {
    bool brokenSegments = false;
-    for( SCH_ITEM* item = GetDrawItems(); item != NULL; item = item->Next() )
+    for( SCH_ITEM* item = m_drawList.begin(); item != NULL; item = item->Next() )
    {
        if( item->Type() == SCH_JUNCTION_T )
        {
@@ -1013,7 +940,7 @@ bool SCH_SCREEN::BreakSegmentsOnJunctions()
 int SCH_SCREEN::GetNode( const wxPoint& aPosition, EDA_ITEMS& aList )
 {
-    for( SCH_ITEM* item = GetDrawItems(); item != NULL; item = item->Next() )
+    for( SCH_ITEM* item = m_drawList.begin(); item != NULL; item = item->Next() )
    {
        if( item->Type() == SCH_LINE_T && item->HitTest( aPosition )
            && (item->GetLayer() == LAYER_BUS || item->GetLayer() == LAYER_WIRE) )
@@ -1032,7 +959,7 @@ int SCH_SCREEN::GetNode( const wxPoint& aPosition, EDA_ITEMS& aList )
 SCH_LINE* SCH_SCREEN::GetWireOrBus( const wxPoint& aPosition )
 {
-    for( SCH_ITEM* item = GetDrawItems(); item != NULL; item = item->Next() )
+    for( SCH_ITEM* item = m_drawList.begin(); item != NULL; item = item->Next() )
    {
        if( (item->Type() == SCH_LINE_T) && item->HitTest( aPosition )
            && (item->GetLayer() == LAYER_BUS || item->GetLayer() == LAYER_WIRE) )
@@ -1048,7 +975,7 @@ SCH_LINE* SCH_SCREEN::GetWireOrBus( const wxPoint& aPosition )
 SCH_LINE* SCH_SCREEN::GetLine( const wxPoint& aPosition, int aAccuracy, int aLayer,
                               SCH_LINE_TEST_T aSearchType )
 {
-    for( SCH_ITEM* item = GetDrawItems(); item != NULL; item = item->Next() )
+    for( SCH_ITEM* item = m_drawList.begin(); item != NULL; item = item->Next() )
    {
        if( item->Type() != SCH_LINE_T )
            continue;
@@ -1081,7 +1008,7 @@ SCH_LINE* SCH_SCREEN::GetLine( const wxPoint& aPosition, int aAccuracy, int aLay
 SCH_TEXT* SCH_SCREEN::GetLabel( const wxPoint& aPosition, int aAccuracy )
 {
-    for( SCH_ITEM* item = GetDrawItems(); item != NULL; item = item->Next() )
+    for( SCH_ITEM* item = m_drawList.begin(); item != NULL; item = item->Next() )
    {
        switch( item->Type() )
        {
@@ -1106,7 +1033,7 @@ bool SCH_SCREEN::SetComponentFootprint( SCH_SHEET_PATH* aSheetPath, const wxStri
    SCH_COMPONENT* component;
    bool           found = false;
-    for( SCH_ITEM* item = GetDrawItems(); item != NULL; item = item->Next() )
+    for( SCH_ITEM* item = m_drawList.begin(); item != NULL; item = item->Next() )
    {
        if( item->Type() != SCH_COMPONENT_T )
            continue;
@@ -1179,7 +1106,7 @@ int SCH_SCREEN::GetConnection( const wxPoint& aPosition, PICKED_ITEMS_LIST& aLis
    {
        SCH_LINE* segment;
-        for( item = GetDrawItems(); item != NULL; item = item->Next() )
+        for( item = m_drawList.begin(); item != NULL; item = item->Next() )
        {
            if( !(item->GetFlags() & SELECTEDNODE) )
                continue;
@@ -1191,7 +1118,7 @@ int SCH_SCREEN::GetConnection( const wxPoint& aPosition, PICKED_ITEMS_LIST& aLis
        }
        // Search all attached wires (i.e wire with one new dangling end )
-        for( item = GetDrawItems(); item != NULL; item = item->Next() )
+        for( item = m_drawList.begin(); item != NULL; item = item->Next() )
        {
            bool noconnect = false;
@@ -1210,7 +1137,7 @@ int SCH_SCREEN::GetConnection( const wxPoint& aPosition, PICKED_ITEMS_LIST& aLis
            /* If the wire start point is connected to a wire that was already found
             * and now is not connected, add the wire to the list. */
-            for( tmp = GetDrawItems(); tmp != NULL; tmp = tmp->Next() )
+            for( tmp = m_drawList.begin(); tmp != NULL; tmp = tmp->Next() )
            {
                // Ensure tmp is a previously deleted segment:
                if( ( tmp->GetFlags() & STRUCT_DELETED ) == 0 )
@@ -1234,7 +1161,7 @@ int SCH_SCREEN::GetConnection( const wxPoint& aPosition, PICKED_ITEMS_LIST& aLis
            /* If the wire end point is connected to a wire that has already been found
             * and now is not connected, add the wire to the list. */
-            for( tmp = GetDrawItems(); tmp != NULL; tmp = tmp->Next() )
+            for( tmp = m_drawList.begin(); tmp != NULL; tmp = tmp->Next() )
            {
                // Ensure tmp is a previously deleted segment:
                if( ( tmp->GetFlags() & STRUCT_DELETED ) == 0 )
@@ -1265,13 +1192,13 @@ int SCH_SCREEN::GetConnection( const wxPoint& aPosition, PICKED_ITEMS_LIST& aLis
                ITEM_PICKER picker( item, UR_DELETED );
                aList.PushItem( picker );
-                item = GetDrawItems();
+                item = m_drawList.begin();
            }
        }
        // Get redundant junctions (junctions which connect < 3 end wires
        // and no pin)
-        for( item = GetDrawItems(); item != NULL; item = item->Next() )
+        for( item = m_drawList.begin(); item != NULL; item = item->Next() )
        {
            if( item->GetFlags() & STRUCT_DELETED )
                continue;
@@ -1293,7 +1220,7 @@ int SCH_SCREEN::GetConnection( const wxPoint& aPosition, PICKED_ITEMS_LIST& aLis
            }
        }
-        for( item = GetDrawItems(); item != NULL;  item = item->Next() )
+        for( item = m_drawList.begin(); item != NULL;  item = item->Next() )
        {
            if( item->GetFlags() & STRUCT_DELETED )
                continue;
@@ -1560,7 +1487,7 @@ void SCH_SCREEN::Show( int nestLevel, std::ostream& os ) const
    // for now, make it look like XML, expand on this later.
    NestedSpace( nestLevel, os ) << '<' << GetClass().Lower().mb_str() << ">\n";
-    for( EDA_ITEM* item = m_drawList;  item;  item = item->Next() )
+    for( EDA_ITEM* item = m_drawList.begin();  item != NULL;  item = item->Next() )
    {
        item->Show( nestLevel+1, os );
    }

--- a/eeschema/sch_sheet.cpp
+++ b/eeschema/sch_sheet.cpp
@@ -2,7 +2,6 @@
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2009 Jean-Pierre Charras, jaen-pierre.charras@gipsa-lab.inpg.com
- * Copyright (C) 2011 Wayne Stambaugh <stambaughw@verizon.net>
 * Copyright (C) 1992-2011 Kicad Developers, see AUTHORS.txt for contributors.
 *
 * This program is free software; you can redistribute it and/or

--- a/eeschema/sch_sheet.h
+++ b/eeschema/sch_sheet.h
@@ -2,7 +2,6 @@
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2009 Jean-Pierre Charras, jaen-pierre.charras@gipsa-lab.inpg.com
- * Copyright (C) 2011 Wayne Stambaugh <stambaughw@verizon.net>
 * Copyright (C) 1992-2011 KiCad Developers, see AUTHORS.txt for contributors.
 *
 * This program is free software; you can redistribute it and/or

--- a/eeschema/sch_sheet_pin.cpp
+++ b/eeschema/sch_sheet_pin.cpp
@@ -2,7 +2,6 @@
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2006 Jean-Pierre Charras, jaen-pierre.charras@gipsa-lab.inpg.com
- * Copyright (C) 2011 Wayne Stambaugh <stambaughw@verizon.net>
 * Copyright (C) 1992-2011 KiCad Developers, see AUTHORS.txt for contributors.
 *
 * This program is free software; you can redistribute it and/or

--- a/eeschema/sch_text.cpp
+++ b/eeschema/sch_text.cpp
@@ -2,7 +2,6 @@
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2009 Jean-Pierre Charras, jaen-pierre.charras@gipsa-lab.inpg.com
- * Copyright (C) 2011 Wayne Stambaugh <stambaughw@verizon.net>
 * Copyright (C) 1992-2011 KiCad Developers, see AUTHORS.txt for contributors.
 *
 * This program is free software; you can redistribute it and/or

--- a/eeschema/sch_text.h
+++ b/eeschema/sch_text.h
@@ -2,7 +2,6 @@
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2009 Jean-Pierre Charras, jaen-pierre.charras@gipsa-lab.inpg.com
- * Copyright (C) 2011 Wayne Stambaugh <stambaughw@verizon.net>
 * Copyright (C) 1992-2011 KiCad Developers, see AUTHORS.txt for contributors.
 *
 * This program is free software; you can redistribute it and/or

--- a/eeschema/schedit.cpp
+++ b/eeschema/schedit.cpp
@@ -178,12 +178,27 @@ void SCH_EDIT_FRAME::Process_Special_Functions( wxCommandEvent& event )
    case ID_POPUP_SCH_BREAK_WIRE:
    {
+        DLIST< SCH_ITEM > oldWires;
+        oldWires.SetOwnership( false );      // Prevent DLIST for deleting items in destructor.
        m_canvas->MoveCursorToCrossHair();
-        SCH_ITEM* oldWiresList = screen->ExtractWires( true );
+        screen->ExtractWires( oldWires, true );
        screen->BreakSegment( screen->GetCrossHairPosition() );
-        if( oldWiresList )
+        if( oldWires.GetCount() != 0 )
-            SaveCopyInUndoList( oldWiresList, UR_WIRE_IMAGE );
+        {
+            PICKED_ITEMS_LIST oldItems;
+            oldItems.m_Status = UR_WIRE_IMAGE;
+            while( oldWires.GetCount() != 0 )
+            {
+                ITEM_PICKER picker = ITEM_PICKER( oldWires.PopFront(), UR_WIRE_IMAGE );
+                oldItems.PushItem( picker );
+            }
+            SaveCopyInUndoList( oldItems, UR_WIRE_IMAGE );
+        }
        screen->TestDanglingEnds( m_canvas, &dc );
    }

--- a/eeschema/schematic_undo_redo.cpp
+++ b/eeschema/schematic_undo_redo.cpp
@@ -2,7 +2,6 @@
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2004 Jean-Pierre Charras, jaen-pierre.charras@gipsa-lab.inpg.com
- * Copyright (C) 2008-2011 Wayne Stambaugh <stambaughw@verizon.net>
 * Copyright (C) 2004-2011 KiCad Developers, see change_log.txt for contributors.
 *
 * This program is free software; you can redistribute it and/or
@@ -112,13 +111,11 @@ void SCH_EDIT_FRAME::SaveCopyInUndoList( SCH_ITEM*      aItem,
                                         UNDO_REDO_T    aCommandType,
                                         const wxPoint& aTransformPoint )
 {
-    /* Does not save a null item.
+    /* Does not save a null item or a UR_WIRE_IMAGE command type.  UR_WIRE_IMAGE commands
-     * but if aCommandType == UR_WIRE_IMAGE, we must save null item.
+     * are handled by the overloaded version of SaveCopyInUndoList that takes a reference
-     * It happens for the first wire entered in schematic:
+     * to a PICKED_ITEMS_LIST.
-     * To undo this first command, the previous state is a NULL item,
-     * and we accept this
     */
-    if( aItem == NULL && ( aCommandType != UR_WIRE_IMAGE ) )
+    if( aItem == NULL || aCommandType == UR_WIRE_IMAGE )
        return;
    PICKED_ITEMS_LIST* commandToUndo = new PICKED_ITEMS_LIST();
@@ -137,7 +134,6 @@ void SCH_EDIT_FRAME::SaveCopyInUndoList( SCH_ITEM*      aItem,
        break;
    case UR_NEW:
-    case UR_WIRE_IMAGE:
    case UR_DELETED:
    case UR_ROTATED:
    case UR_MOVED:
@@ -145,13 +141,9 @@ void SCH_EDIT_FRAME::SaveCopyInUndoList( SCH_ITEM*      aItem,
        break;
    default:
-    {
+        wxFAIL_MSG( wxString::Format( wxT( "SaveCopyInUndoList() error (unknown code %X)" ),
-        wxString msg;
+                                      aCommandType ) );
-        msg.Printf( wxT( "SaveCopyInUndoList() error (unknown code %X)" ),
+        break;
-                    aCommandType );
-        wxMessageBox( msg );
-    }
-    break;
    }
    if( commandToUndo->GetCount() )
@@ -163,7 +155,9 @@ void SCH_EDIT_FRAME::SaveCopyInUndoList( SCH_ITEM*      aItem,
        GetScreen()->ClearUndoORRedoList( GetScreen()->m_RedoList );
    }
    else
+    {
        delete commandToUndo;
+    }
 }
@@ -174,6 +168,7 @@ void SCH_EDIT_FRAME::SaveCopyInUndoList( PICKED_ITEMS_LIST& aItemsList,
    PICKED_ITEMS_LIST* commandToUndo = new PICKED_ITEMS_LIST();
    commandToUndo->m_TransformPoint = aTransformPoint;
+    commandToUndo->m_Status = aTypeCommand;
    // Copy picker list:
    commandToUndo->CopyList( aItemsList );
@@ -202,6 +197,7 @@ void SCH_EDIT_FRAME::SaveCopyInUndoList( PICKED_ITEMS_LIST& aItemsList,
             */
            if( commandToUndo->GetPickedItemLink( ii ) == NULL )
                commandToUndo->SetPickedItemLink( DuplicateStruct( item, true ), ii );
            wxASSERT( commandToUndo->GetPickedItemLink( ii ) );
            break;
@@ -212,6 +208,7 @@ void SCH_EDIT_FRAME::SaveCopyInUndoList( PICKED_ITEMS_LIST& aItemsList,
        case UR_NEW:
        case UR_DELETED:
        case UR_EXCHANGE_T:
+        case UR_WIRE_IMAGE:
            break;
        default:
@@ -220,7 +217,7 @@ void SCH_EDIT_FRAME::SaveCopyInUndoList( PICKED_ITEMS_LIST& aItemsList,
        }
    }
-    if( commandToUndo->GetCount() )
+    if( commandToUndo->GetCount() || aTypeCommand == UR_WIRE_IMAGE )
    {
        /* Save the copy in undo list */
        GetScreen()->PushCommandToUndoList( commandToUndo );
@@ -229,7 +226,9 @@ void SCH_EDIT_FRAME::SaveCopyInUndoList( PICKED_ITEMS_LIST& aItemsList,
        GetScreen()->ClearUndoORRedoList( GetScreen()->m_RedoList );
    }
    else    // Should not occur
+    {
        delete commandToUndo;
+    }
 }
@@ -238,9 +237,36 @@ void SCH_EDIT_FRAME::PutDataInPreviousState( PICKED_ITEMS_LIST* aList, bool aRed
    SCH_ITEM* item;
    SCH_ITEM* alt_item;
-    // Undo in the reverse order of list creation: (this can allow stacked
+    // Exchange the current wires, buses, and junctions with the copy save by the last edit.
-    // changes like the same item can be changes and deleted in the same
+    if( aList->m_Status == UR_WIRE_IMAGE )
-    // complex command
+    {
+        DLIST< SCH_ITEM > oldWires;
+        // Prevent items from being deleted when the DLIST goes out of scope.
+        oldWires.SetOwnership( false );
+        // Remove all of the wires, buses, and junctions from the current screen.
+        GetScreen()->ExtractWires( oldWires, false );
+        // Copy the saved wires, buses, and junctions to the current screen.
+        for( unsigned int i = 0;  i < aList->GetCount();  i++ )
+            GetScreen()->Append( (SCH_ITEM*) aList->GetPickedItem( i ) );
+        aList->ClearItemsList();
+        // Copy the previous wires, buses, and junctions to the picked item list for the
+        // redo operation.
+        while( oldWires.GetCount() != 0 )
+        {
+            ITEM_PICKER picker = ITEM_PICKER( oldWires.PopFront(), UR_WIRE_IMAGE );
+            aList->PushItem( picker );
+        }
+        return;
+    }
+    // Undo in the reverse order of list creation: (this can allow stacked changes like the
+    // same item can be changes and deleted in the same complex command.
    for( int ii = aList->GetCount() - 1; ii >= 0; ii--  )
    {
        item = (SCH_ITEM*) aList->GetPickedItem( ii );
@@ -253,18 +279,21 @@ void SCH_EDIT_FRAME::PutDataInPreviousState( PICKED_ITEMS_LIST* aList, bool aRed
        switch( aList->GetPickedItemStatus( ii ) )
        {
        case UR_CHANGED: /* Exchange old and new data for each item */
+            // tmp = item->Clone();
+            // *item = *image;
+            // *image = *tmp;
+            // delete tmp;
            item->SwapData( image );
            break;
        case UR_NEW:     /* new items are deleted */
            aList->SetPickedItemStatus( UR_DELETED, ii );
-            GetScreen()->RemoveFromDrawList( item );
+            GetScreen()->Remove( item );
            break;
-        case UR_DELETED: /* deleted items are put in EEdrawList, as new items */
+        case UR_DELETED: /* deleted items are put in the draw item list, as new items */
            aList->SetPickedItemStatus( UR_NEW, ii );
-            item->SetNext( GetScreen()->GetDrawItems() );
+            GetScreen()->Append( item );
-            GetScreen()->SetDrawItems( item );
            break;
        case UR_MOVED:
@@ -275,55 +304,32 @@ void SCH_EDIT_FRAME::PutDataInPreviousState( PICKED_ITEMS_LIST* aList, bool aRed
            break;
        case UR_MIRRORED_Y:
-        {
+            item->Mirror_Y( aList->m_TransformPoint.x );
-            wxPoint mirrorPoint = aList->m_TransformPoint;
+            break;
-            item->Mirror_Y( mirrorPoint.x );
-        }
-        break;
        case UR_MIRRORED_X:
-        {
+            item->Mirror_X( aList->m_TransformPoint.y );
-            wxPoint mirrorPoint = aList->m_TransformPoint;
+            break;
-            item->Mirror_X( mirrorPoint.y );
-        }
-        break;
        case UR_ROTATED:
-        {
            // To undo a rotate 90 deg transform we must rotate 270 deg to undo
            // and 90 deg to redo:
-            wxPoint RotationPoint = aList->m_TransformPoint;
+            item->Rotate( aList->m_TransformPoint );
-            item->Rotate( RotationPoint );
            if( aRedoCommand )
                break;  // A only one rotate transform is OK
-            // Make 3 rotate 90 deg transforms is this is actually an undo command
-            item->Rotate( RotationPoint );
-            item->Rotate( RotationPoint );
-        }
-        break;
-        case UR_WIRE_IMAGE:
-            /* Exchange the current wires and the old wires */
-            alt_item = GetScreen()->ExtractWires( false );
-            aList->SetPickedItem( alt_item, ii );
-            while( item )
-            {
-                SCH_ITEM* nextitem = item->Next();
-                item->SetNext( GetScreen()->GetDrawItems() );
-                GetScreen()->SetDrawItems( item );
-                item->ClearFlags();
-                item = nextitem;
-            }
+            // Make 3 rotate 90 deg transforms is this is actually an undo command
+            item->Rotate( aList->m_TransformPoint );
+            item->Rotate( aList->m_TransformPoint );
            break;
        case UR_EXCHANGE_T:
            alt_item = (SCH_ITEM*) aList->GetPickedItemLink( ii );
            alt_item->SetNext( NULL );
            alt_item->SetBack( NULL );
-            GetScreen()->RemoveFromDrawList( item );
+            GetScreen()->Remove( item );
-            GetScreen()->AddToDrawList( alt_item );
+            GetScreen()->Append( alt_item );
            aList->SetPickedItem( alt_item, ii );
            aList->SetPickedItemLink( item, ii );
            break;

--- a/eeschema/schframe.cpp
+++ b/eeschema/schframe.cpp
@@ -2,7 +2,6 @@
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2009 Jean-Pierre Charras, jaen-pierre.charras@gipsa-lab.inpg.com
- * Copyright (C) 2011 Wayne Stambaugh <stambaughw@verizon.net>
 * Copyright (C) 1992-2011 KiCad Developers, see AUTHORS.txt for contributors.
 *
 * This program is free software; you can redistribute it and/or
@@ -930,7 +929,7 @@ void SCH_EDIT_FRAME::addCurrentItemToList( wxDC* aDC )
        if( undoItem == item )
        {
            if( !screen->CheckIfOnDrawList( item ) )  // don't want a loop!
-                screen->AddToDrawList( item );
+                screen->Append( item );
            SetRepeatItem( item );

--- a/eeschema/sheet.cpp
+++ b/eeschema/sheet.cpp
@@ -2,7 +2,6 @@
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2006 Jean-Pierre Charras, jaen-pierre.charras@gipsa-lab.inpg.com
- * Copyright (C) 2009-2011 Wayne Stambaugh <stambaughw@verizon.net>
 * Copyright (C) 2004-2011 KiCad Developers, see change_log.txt for contributors.
 *
 * This program is free software; you can redistribute it and/or
@@ -282,14 +281,14 @@ static void ExitSheet( EDA_DRAW_PANEL* aPanel, wxDC* aDC )
    }
    else if( item->IsMoving() || item->IsResized() )
    {
-        screen->RemoveFromDrawList( item );
+        screen->Remove( item );
        delete item;
        item = parent->GetUndoItem();
        wxCHECK_RET( item != NULL, wxT( "Cannot restore undefined last sheet item." ) );
-        screen->AddToDrawList( item );
+        screen->Append( item );
        // the owner of item is no more parent, this is the draw list of screen:
        parent->SetUndoItem( NULL );

--- a/include/class_sch_screen.h
+++ b/include/class_sch_screen.h
@@ -2,7 +2,6 @@
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2009 Jean-Pierre Charras, jaen-pierre.charras@gipsa-lab.inpg.com
- * Copyright (C) 2011 Wayne Stambaugh <stambaughw@verizon.net>
 * Copyright (C) 1992-2011 KiCad Developers, see AUTHORS.txt for contributors.
 *
 * This program is free software; you can redistribute it and/or
@@ -32,6 +31,7 @@
 #define CLASS_SCREEN_H
 #include <macros.h>
+#include <dlist.h>
 #include <sch_item_struct.h>
 #include <class_base_screen.h>
 #include <class_title_block.h>
@@ -73,8 +73,8 @@ class SCH_SCREEN : public BASE_SCREEN
    /// Position of the origin axis, which is used in exports mostly, but not yet in EESCHEMA
    wxPoint     m_originAxisPosition;
-    SCH_ITEM*   m_drawList;     ///< Object list for the screen.
+    DLIST< SCH_ITEM > m_drawList;     ///< Object list for the screen.
-                                /// @todo use DLIST<SCH_ITEM> or superior container
+                                      /// @todo use DLIST<SCH_ITEM> or superior container
    /**
     * Function addConnectedItemsToBlock
@@ -122,8 +122,17 @@ public:
     * Function GetDrawItems().
     * @return - A pointer to the first item in the linked list of draw items.
     */
-    SCH_ITEM* GetDrawItems() const          { return m_drawList; }
+    SCH_ITEM* GetDrawItems() const          { return m_drawList.begin(); }
-    void SetDrawItems( SCH_ITEM* aItem )    { m_drawList = aItem; }
+    void Append( SCH_ITEM* aItem )          { m_drawList.Append( aItem ); }
+    /**
+     * Function Append
+     * adds \a aList of SCH_ITEM objects to the list for draw items for the sheet.
+     *
+     * @param aList A reference to a #DLIST containing the #SCH_ITEM to add to the sheet.
+     */
+    void Append( DLIST< SCH_ITEM >& aList ) { m_drawList.Append( aList ); }
    /**
     * Function GetCurItem
@@ -184,11 +193,13 @@ public:
    void Plot( PLOTTER* aPlotter );
    /**
-     * Remove \a aItem from the schematic associated with this screen.
+     * Function Remove
+     * removes \a aItem from the schematic associated with this screen.
     *
-     * @param aItem - Item to be removed from schematic.
+     * @note The removed item is not deleted.  It is only unlinked from the item list.
+     * @param aItem Item to be removed from schematic.
     */
-    void RemoveFromDrawList( SCH_ITEM* aItem );
+    void Remove( SCH_ITEM* aItem );
    /**
     * Function DeleteItem
@@ -201,8 +212,6 @@ public:
    bool CheckIfOnDrawList( SCH_ITEM* st );
-    void AddToDrawList( SCH_ITEM* st );
    /**
     * Function SchematicCleanUp
     * performs routine schematic cleaning including breaking wire and buses and
@@ -226,23 +235,24 @@ public:
    /**
     * Function ExtractWires
     * extracts the old wires, junctions and buses.  If \a aCreateCopy is true, replace
-     * them with a copy.  Old item must be put in undo list, and the new ones can be
+     * extracted items with a copy of the original.  Old items are to be put in undo list,
-     * modified by clean up safely.  If an abort command is made, old wires must be put
+     * and the new ones can be modified by clean up safely.  If an abort draw segmat command
-     * in GetDrawItems(), and copies must be deleted.  This is because previously stored
+     * is made, the old wires must be put back into #m_drawList, and the copies must be
-     * undo commands can handle pointers on wires or buses, and we do not delete wires or
+     * deleted.  This is because previously stored undo commands can handle pointers on wires
-     * buss-es, we must put they in undo list.
+     * or buses, and we do not delete wires or buses, we must put them in undo list.
     *
-     * Because cleanup delete and/or modify bus and wires, the it is easier is to put
+     * Because cleanup deletes and/or modify bus and wires, it is easier is to put
-     * all wires in undo list and use a new copy of wires for cleanup.
+     * all the existing  wires in undo list and use a new copy of wires for cleanup.
     */
-    SCH_ITEM* ExtractWires( bool aCreateCopy );
+    void ExtractWires( DLIST< SCH_ITEM >& aList, bool aCreateCopy );
    /**
     * Function ReplaceWires
-     * replaces all of the wires and junction in the screen with \a aWireList.
+     * replaces all of the wires, buses, and junctions in the screen with \a aWireList.
-     * @param aWireList List of wire to replace the existing wires with.
+     *
+     * @param aWireList List of wires to replace the existing wires with.
     */
-    void ReplaceWires( SCH_ITEM* aWireList );
+    void ReplaceWires( DLIST< SCH_ITEM >& aWireList );
    /**
     * Function MarkConnections

--- a/include/dlist.h
+++ b/include/dlist.h
@@ -63,22 +63,31 @@ protected:
    /**
     * Function append
     * adds \a aNewElement to the end of the list.
+     * @param aNewElement The element to insert.
     */
    void append( EDA_ITEM* aNewElement );
+    /**
+     * Function append
+     * adds \a aList to the end of the list.
+     * @param aList The list to aList.
+     */
+    void append( DHEAD& aList );
    /**
     * Function insert
-     * puts aNewElement just in front of aElementAfterMe in the list sequence.
+     * puts \a aNewElement just in front of \a aElementAfterMe in the list sequence.
-     * If aElementAfterMe is NULL, then simply append().
+     * If \a aElementAfterMe is NULL, then simply append().
     * @param aNewElement The element to insert.
     * @param aElementAfterMe The element to insert \a aNewElement before,
-     *  if NULL then append aNewElement onto end of list.
+     *                        if NULL then append \a aNewElement onto end of list.
     */
    void insert( EDA_ITEM* aNewElement, EDA_ITEM* aElementAfterMe );
    /**
     * Function insert
-     * puts aNewElement in front of list sequence.
+     * puts \a aNewElement in front of list sequence.
+     * @param aNewElement The element to insert.
     */
    void insert( EDA_ITEM* aNewElement )
    {
@@ -88,6 +97,7 @@ protected:
    /**
     * Function remove
     * removes \a aElement from the list, but does not delete it.
+     * @param aElement The element to remove.
     */
    void remove( EDA_ITEM* aElement );
@@ -162,16 +172,30 @@ public:
    /**
     * Function Append
     * adds \a aNewElement to the end of the list.
+     * @param aNewElement The element to insert.
     */
    void Append( T* aNewElement )
    {
        append( aNewElement );
    }
+    /**
+     * Function Append
+     * adds \a aList to the end of the list.
+     * @param aList The list to append to the end of the list.
+     */
+    void Append( DLIST& aList )
+    {
+        append( aList );
+    }
    /**
     * Function Insert
-     * puts aNewElement just in front of aElementAfterMe in the list sequence.
+     * puts \a aNewElement just in front of \a aElementAfterMe in the list sequence.
     * If aElementAfterMe is NULL, then simply Append()
+     * @param aNewElement The element to insert.
+     * @param aElementAfterMe The element to insert \a aNewElement before,
+     *                        if NULL then append \a aNewElement onto end of list.
     */
    void Insert( T* aNewElement, T* aElementAfterMe )
    {
@@ -181,6 +205,7 @@ public:
    /**
     * Function Remove
     * removes \a aElement from the list, but does not delete it.
+     * @param aElement The element to remove from the list.
     * @return T* - the removed element, so you can easily delete it upon return.
     */
    T* Remove( T* aElement )
@@ -210,6 +235,7 @@ public:
    /**
     * Function PushFront
     * puts aNewElement at front of list sequence.
+     * @param aNewElement The element to insert at the front of the list.
     */
    void PushFront( T* aNewElement )
    {
@@ -219,6 +245,7 @@ public:
    /**
     * Function PushBack
     * puts aNewElement at the end of the list sequence.
+     * @param aNewElement The element to push to the end of the list.
     */
    void PushBack( T* aNewElement )
    {

--- a/include/sch_item_struct.h
+++ b/include/sch_item_struct.h
@@ -2,7 +2,6 @@
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2004 Jean-Pierre Charras, jaen-pierre.charras@gipsa-lab.inpg.com
- * Copyright (C) 2008-2011 Wayne Stambaugh <stambaughw@verizon.net>
 * Copyright (C) 2004-2011 KiCad Developers, see change_log.txt for contributors.
 *
 * This program is free software; you can redistribute it and/or
@@ -352,8 +351,6 @@ public:
    virtual bool operator <( const SCH_ITEM& aItem ) const;
-    virtual SCH_ITEM& operator=( const SCH_ITEM& aItem );
    /**
     * @note - The DoXXX() functions below are used to enforce the interface while retaining
     *         the ability of change the implementation behavior of derived classes.  See