[Fixes bug #1176847] Display the selection layer on top of the active

layer in the layers list widget.

This solution fixes the original issue (bug #1175733), and I reverted
the changes that caused a regression (bug #1176847).

Pinta.Core/Classes/Document.cs

@@ -388,7 +388,7 @@ public UserLayer DuplicateCurrentLayer()
 			return layer;
 		}
 
-		public void FinishSelection (CompoundHistoryItem compoundAction)
+		public void FinishSelection ()
 		{
 			// We don't have an uncommitted layer, abort
 			if (!ShowSelectionLayer)
@@ -406,11 +406,7 @@ public void FinishSelection (CompoundHistoryItem compoundAction)
 			DestroySelectionLayer ();
 			Workspace.Invalidate ();
 
-			if (compoundAction != null) {
-				compoundAction.Push (hist);
-			} else {
-				Workspace.History.PushNewItem (hist);
-			}
+			Workspace.History.PushNewItem (hist);
 		}
 
 		// Flatten image
@@ -838,8 +834,9 @@ public void Paste (bool toNewLayer, int x = 0, int y = 0)
 			                                    new Cairo.Rectangle (x, y, cbImage.Width, cbImage.Height));
 			ShowSelection = true;
 
+			Workspace.Invalidate ();
+
 			paste_action.Push (new PasteHistoryItem (cbImage, old_selection, old_show_selection));
-			FinishSelection(paste_action);
 			History.PushNewItem (paste_action);
 		}
 

Pinta.Core/Managers/LayerManager.cs

@@ -97,7 +97,7 @@ public void SetCurrentLayer(UserLayer layer)
 
 		public void FinishSelection ()
 		{
-			PintaCore.Workspace.ActiveDocument.FinishSelection (null);
+			PintaCore.Workspace.ActiveDocument.FinishSelection ();
 		}
 
 		// Adds a new layer above the current one

Pinta.Gui.Widgets/Widgets/Layers/LayersListWidget.cs

@@ -40,6 +40,11 @@ public class LayersListWidget : ScrolledWindow
 	{
 		private TreeView tree;
 		private TreeStore store;
+
+		// For the active layer, we also draw the selection layer on top of it,
+		// so we can't directly use that layer's surface.
+		private Cairo.ImageSurface active_layer_surface;
+		private CanvasRenderer canvas_renderer = new CanvasRenderer (false);
 
 		private const int store_index_thumbnail = 0;
 		private const int store_index_name = 1;
@@ -194,11 +199,34 @@ public void Reset ()
 		{
 			store.Clear ();
 
+			if (active_layer_surface != null) {
+				active_layer_surface.Dispose ();
+				active_layer_surface = null;
+			}
+
 			if (!PintaCore.Workspace.HasOpenDocuments)
 				return;
+
+			var doc = PintaCore.Workspace.ActiveDocument;
 
-			foreach (var layer in (PintaCore.Workspace.ActiveDocument.UserLayers as IEnumerable<Layer>).Reverse ())
-				store.AppendValues (layer.Surface, layer.Name, !layer.Hidden, layer);
+			foreach (var layer in (doc.UserLayers as IEnumerable<Layer>).Reverse ()) {
+				var surf = layer.Surface;
+
+				// Draw the selection layer on top of the active layer.
+				if (layer == doc.CurrentUserLayer && doc.ShowSelectionLayer) {
+					active_layer_surface = new Cairo.ImageSurface (Cairo.Format.Argb32, thumbnail_width,
+					                                               thumbnail_height);
+					canvas_renderer.Initialize (doc.ImageSize,
+					                            new Gdk.Size (thumbnail_width, thumbnail_height));
+
+					var layers = new List<Layer> { layer, doc.SelectionLayer };
+					canvas_renderer.Render (layers, active_layer_surface, Gdk.Point.Zero);
+
+					surf = active_layer_surface;
+				}
+
+				store.AppendValues (surf, layer.Name, !layer.Hidden, layer);
+			}
 
 			SelectLayerInTreeView (PintaCore.Layers.Count - PintaCore.Layers.CurrentLayerIndex - 1);
 		}

Pinta.Tools/Tools/MoveSelectedTool.cs

@@ -141,7 +141,7 @@ protected override void OnFinishTransform ()
 		protected override void OnCommit ()
 		{
 			try {
-				PintaCore.Workspace.ActiveDocument.FinishSelection (null);
+				PintaCore.Workspace.ActiveDocument.FinishSelection ();
 			} catch (Exception) {
 				// Ignore an error where ActiveDocument fails.
 			}
@@ -152,7 +152,7 @@ protected override void OnDeactivated ()
 			base.OnDeactivated ();
 
 			if (PintaCore.Workspace.HasOpenDocuments) {
-				PintaCore.Workspace.ActiveDocument.FinishSelection (null);
+				PintaCore.Workspace.ActiveDocument.FinishSelection ();
 			}
 		}
 	}