I’m trying to figure out a way to have a selected button/item extend past the main window and ‘connect’ to the spawned window. I’m thinking that a transparent window behind the ‘toolbar’ window and the spawned item. Am I on the right track?
Here is what I’m trying to do:

Thanks for the input.
You look like you on the right track. A control cannot extended beyond the bounds of a window so you would have to make the window transparent and color only part of the window to make it look as if the selected item is extended beyond the window bounds.