Add helpful context menus (right click) to the position editing screen

- Right click on widget: Opening widget settings, setting anchor or deactivating the widget
- Right click on empty space: Enabling widgets

src/main/java/de/shiewk/widgets/Anchor.java

@@ -56,6 +56,6 @@ public enum Anchor {
                 return anchor;
             }
         }
-        return Anchor.TOP_LEFT;
+        return null;
     }
 }