Check for negative height or width before changing object since it will cause an exception

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

@@ -394,11 +394,13 @@ namespace ICSharpCode.WpfDesign.Designer
 					}
 					else
 					{
+						if (info.OriginalBounds.Width + dx >= 0 && info.OriginalBounds.Height + dy >= 0)  {
 							info.Bounds = new Rect(info.OriginalBounds.Left,
 							                       info.OriginalBounds.Top,
 							                       info.OriginalBounds.Width + dx,
 							                       info.OriginalBounds.Height + dy);
 						}
+					}
 					
 					placementOp.CurrentContainerBehavior.SetPosition(info);
 				}