Moving controls several steps by holding down arrow keys is now working again.

Removed canvas special handling in DesignPanel and instead letting each placement behavior handle its own special needs, and handling the Canvas issue by overriding GetPosition in CanvasPlacementSupport instead.
Fixed SetPosition in CanvasPlacementSupport so Left/Top properties have priority over Right/Bottom, as this is the priority that the runtime uses.

src/AddIns/DisplayBindings/WpfDesign/WpfDesign.Designer/Project/DesignPanel.cs

@@ -377,28 +377,35 @@ namespace ICSharpCode.WpfDesign.Designer
 					placementOp = PlacementOperation.Start(Context.Services.Selection.SelectedItems, PlacementType.Move);
 				}
 				
+				switch (e.Key) {
+					case Key.Left:
+						dx += Keyboard.IsKeyDown(Key.LeftShift) ? -10 : -1;
+						break;
+					case Key.Up:
+						dy += Keyboard.IsKeyDown(Key.LeftShift) ? -10 : -1;
+						break;
+					case Key.Right:
+						dx += Keyboard.IsKeyDown(Key.LeftShift) ? 10 : 1;
+						break;
+					case Key.Down:
+						dy += Keyboard.IsKeyDown(Key.LeftShift) ? 10 : 1;
+						break;
+				}
 				
-				dx = (e.Key == Key.Left) ? Keyboard.IsKeyDown(Key.LeftShift) ? -10 : -1 : 0;
-				dy = (e.Key == Key.Up) ? Keyboard.IsKeyDown(Key.LeftShift) ? -10 : -1 : 0;
-				dx = (e.Key == Key.Right) ? Keyboard.IsKeyDown(Key.LeftShift) ? 10 : 1 : (dx != 0 ? dx : 0);
-                dy = (e.Key == Key.Down) ? Keyboard.IsKeyDown(Key.LeftShift) ? 10 : 1 : (dy != 0 ? dy : 0);
-				double left, top;
 				foreach (PlacementInformation info in placementOp.PlacedItems)
 				{
-                    //Let canvas position preceed bounds definition since there can be a discrepancy between them.
-				    left = IsPropertySet(info.Item.View,Canvas.LeftProperty)?(double)info.Item.Properties.GetAttachedProperty(Canvas.LeftProperty).ValueOnInstance: info.OriginalBounds.Left;
-
-                    top = IsPropertySet(info.Item.View, Canvas.TopProperty) ? (double)info.Item.Properties.GetAttachedProperty(Canvas.TopProperty).ValueOnInstance : info.OriginalBounds.Top;
+					var bounds = info.OriginalBounds;
+					
 					if (!Keyboard.IsKeyDown(Key.LeftCtrl)) {
-						info.Bounds = new Rect(left + dx,
-							top + dy,
-							info.OriginalBounds.Width,
-							info.OriginalBounds.Height);
+						info.Bounds = new Rect(bounds.Left + dx,
+							bounds.Top + dy,
+							bounds.Width,
+							bounds.Height);
 					} else {
-						info.Bounds = new Rect(left,
-							top,
-							info.OriginalBounds.Width + dx,
-							info.OriginalBounds.Height + dy);
+						info.Bounds = new Rect(bounds.Left,
+							bounds.Top,
+							bounds.Width + dx,
+							bounds.Height + dy);
 					}
 					placementOp.CurrentContainerBehavior.SetPosition(info);
 				}

src/AddIns/DisplayBindings/WpfDesign/WpfDesign.Designer/Project/Extensions/CanvasPlacementSupport.cs

@@ -58,6 +58,32 @@ namespace ICSharpCode.WpfDesign.Designer.Extensions
 			extendedView = (FrameworkElement)this.ExtendedItem.View;
 		}
 		
+		public override Rect GetPosition(PlacementOperation operation, DesignItem item)
+		{
+			UIElement child = item.View;
+
+			if (child == null)
+				return Rect.Empty;
+
+			double x, y;
+
+			if (IsPropertySet(child, Canvas.LeftProperty) || !IsPropertySet(child, Canvas.RightProperty)) {
+				x = GetCanvasProperty(child, Canvas.LeftProperty);
+			} else {
+				x = extendedComponent.ActualWidth - GetCanvasProperty(child, Canvas.RightProperty) - child.RenderSize.Width;
+			}
+
+
+			if (IsPropertySet(child, Canvas.TopProperty) || !IsPropertySet(child, Canvas.BottomProperty)) {
+				y = GetCanvasProperty(child, Canvas.TopProperty);
+			} else {
+				y = extendedComponent.ActualHeight - GetCanvasProperty(child, Canvas.BottomProperty) - child.RenderSize.Height;
+			}
+
+			var p = new Point(x, y);
+			return new Rect(p, child.RenderSize);
+		}
+		
 		public override void SetPosition(PlacementInformation info)
 		{
 			base.SetPosition(info);
@@ -66,28 +92,26 @@ namespace ICSharpCode.WpfDesign.Designer.Extensions
 			UIElement child = info.Item.View;
 			Rect newPosition = info.Bounds;
 
-			if (IsPropertySet(child, Canvas.RightProperty))
-			{
+			if (IsPropertySet(child, Canvas.LeftProperty) || !IsPropertySet(child, Canvas.RightProperty)) {
+				if (newPosition.Left != GetCanvasProperty(child, Canvas.LeftProperty)) {
+					info.Item.Properties.GetAttachedProperty(Canvas.LeftProperty).SetValue(newPosition.Left);
+				}
+			} else {
 				var newR = extendedComponent.ActualWidth - newPosition.Right;
 				if (newR != GetCanvasProperty(child, Canvas.RightProperty))
 					info.Item.Properties.GetAttachedProperty(Canvas.RightProperty).SetValue(newR);
 			}
-			else if (newPosition.Left != GetCanvasProperty(child, Canvas.LeftProperty))
-			{
-				info.Item.Properties.GetAttachedProperty(Canvas.LeftProperty).SetValue(newPosition.Left);
-			}
 
 
-			if (IsPropertySet(child, Canvas.BottomProperty))
-			{
+			if (IsPropertySet(child, Canvas.TopProperty) || !IsPropertySet(child, Canvas.BottomProperty)) {
+				if (newPosition.Top != GetCanvasProperty(child, Canvas.TopProperty)) {
+					info.Item.Properties.GetAttachedProperty(Canvas.TopProperty).SetValue(newPosition.Top);
+				}
+			} else {
 				var newB = extendedComponent.ActualHeight - newPosition.Bottom;
 				if (newB != GetCanvasProperty(child, Canvas.BottomProperty))
 					info.Item.Properties.GetAttachedProperty(Canvas.BottomProperty).SetValue(newB);
 			}
-			else if (newPosition.Top != GetCanvasProperty(child, Canvas.TopProperty))
-			{
-				info.Item.Properties.GetAttachedProperty(Canvas.TopProperty).SetValue(newPosition.Top);
-			}
 
 			if (info.Item == Services.Selection.PrimarySelection)
 			{