Undo schematic hierarchy path container changes.

* Boost container release method clobbering sheet pointers causing
  seg faults.

eeschema/sch_screen.cpp

@@ -216,8 +216,6 @@ SCH_ITEM* SCH_SCREEN::ExtractWires( bool CreateCopy )
  */
 bool SCH_SCREEN::SchematicCleanUp( EDA_DRAW_PANEL* aCanvas, wxDC* aDC )
 {
-    wxASSERT( aCanvas != NULL );
-
     SCH_ITEM* DrawList, * TstDrawList;
     bool      Modify = FALSE;
 
@@ -674,11 +672,11 @@ bool SCH_SCREEN::TestDanglingEnds( EDA_DRAW_PANEL* aCanvas, wxDC* aDC )
         {
             item->Draw( aCanvas, aDC, wxPoint( 0, 0 ), g_XorMode );
             item->Draw( aCanvas, aDC, wxPoint( 0, 0 ), GR_DEFAULT_DRAWMODE );
+        }
 
         if( item->IsDangling() )
             hasDanglingEnds = true;
     }
-    }
 
     return hasDanglingEnds;
 }

eeschema/sch_sheet.cpp

@@ -65,6 +65,8 @@ SCH_SHEET::SCH_SHEET( const SCH_SHEET& aSheet ) :
 
 SCH_SHEET::~SCH_SHEET()
 {
+    wxLogDebug( wxT( "Destroying sheet " ) + m_SheetName );
+
     // also, look at the associated sheet & its reference count
     // perhaps it should be deleted also.
     if( m_AssociatedScreen )

eeschema/schframe.cpp

@@ -346,12 +346,23 @@ void SCH_EDIT_FRAME::CreateScreens()
 
 void SCH_EDIT_FRAME::OnCloseWindow( wxCloseEvent& Event )
 {
-    if( m_LibeditFrame && !m_LibeditFrame->Close() )   // Can close component editor?
+    SCH_SHEET_PATH* sheet;
+
+    if( m_LibeditFrame ) // Can close component editor ?
+    {
+        if( !m_LibeditFrame->Close() )
             return;
+    }
 
     SCH_SHEET_LIST SheetList;
 
-    if( SheetList.IsModified() )
+    for( sheet = SheetList.GetFirst(); sheet != NULL; sheet = SheetList.GetNext() )
+    {
+        if( sheet->LastScreen() && sheet->LastScreen()->IsModify() )
+            break;
+    }
+
+    if( sheet )
     {
         wxMessageDialog dialog( this,
                                 _( "Schematic modified, Save before exit ?" ),
@@ -374,7 +385,15 @@ void SCH_EDIT_FRAME::OnCloseWindow( wxCloseEvent& Event )
         }
     }
 
-    SheetList.ClearModifyStatus();
+    for( sheet = SheetList.GetFirst();
+        sheet != NULL;
+        sheet = SheetList.GetNext() )
+    {
+        if( sheet->LastScreen() )
+        {
+            sheet->LastScreen()->ClrModify();
+        }
+    }
 
     if( !g_RootSheet->GetScreen()->GetFileName().IsEmpty()
        && (g_RootSheet->GetScreen()->GetDrawItems() != NULL) )