HeaderBar consuming click with DRAGGABLE_SUBTREE (when focus lost and gained)

[Michael Strauß]

> I've noticed this behaviour as follows with a HeaderBar stage and MenuBar.
>
> If you make the JFX window lose focus, but still keep it visible, note the Menu items are responding to mouse hovers. But the first click is always ignored (i.e., no menu shown). This can be more frustrating than it may sound, when dealing with a lot of popups and secondary window hopping, etc. I assume this is not limited to MenuBar either.
>
> Example and code below. I will browse to Notepad to lose focus. The red circle you see is a click, see how it requires two clicks for the menu to appear when coming back from Notepad. Note this is not the behaviour for "Normal Menu", a menu not inside HeaderBar.


You've set an interactive element (the MenuBar) to be draggable,
that's the source of problem. I don't think that it's worth supporting
the specific scenario of click activation, as you'll soon run into
even more problems (for example, you can drag away the window under an
open menu.

Interactive draggable elements is simply not a supported
configuration. Maybe I should explicitly point this out in the
documentation.