gerbview: fix an issue when using layer list in toolbar to select layer (back...

gerbview: fix an issue when using layer list in toolbar to select layer (back to old layer under Linux)
Refresh screen when active layer is changed from the layer manager.

gerbview/class_gerbview_layer_widget.cpp

@@ -202,9 +202,10 @@ bool GERBER_LAYER_WIDGET::OnLayerSelect( int aLayer )
 {
     // the layer change from the GERBER_LAYER_WIDGET can be denied by returning
     // false from this function.
+    int layer = myframe->getActiveLayer( );
     myframe->setActiveLayer( aLayer, false );
     myframe->syncLayerBox();
-    if(DisplayOpt.ContrastModeDisplay)
+    if( layer != myframe->getActiveLayer( ) )
         myframe->DrawPanel->Refresh();
 
     return true;

gerbview/edit.cpp

@@ -138,8 +138,12 @@ void GERBVIEW_FRAME::Process_Special_Functions( wxCommandEvent& event )
         break;
 
     case ID_TOOLBARH_GERBVIEW_SELECT_LAYER:
-        setActiveLayer(m_SelLayerBox->GetChoice());
-        DrawPanel->ReDraw( &dc, false );
+    {
+        int layer = getActiveLayer( );
+        setActiveLayer(event.GetSelection());
+        if( layer != getActiveLayer( ) )
+            DrawPanel->ReDraw( &dc, false );
+    }
         break;
 
     case ID_TOOLBARH_GERBER_SELECT_TOOL: