Once you create an application and a visual part, you can open a Composition Editor on the part and add a user interface. Upon opening, a Composition Editor shows a window in the main work area, the free-form surface.
To add a user interface to your application:
You'll see a crosshair,
, or a not-available sign,
, when your mouse is over the free-form surface.
A
means that you can drop the part where your mouse is.
A
means that you cannot drop the part.
Generally, user-interface parts can go onto the window. Parts that don't make up the user interface cannot go onto the window; you must drop them on the free-form surface beside the window.