Focus problems with popup menus

[KoBeWi]

Godot version:
b50387c

OS/device including version:
Windows 10

Issue description:
The new popup menus will unfocus the editor, which leads to problems like this

These buttons no longer get hover event (you can see that different button is hovered from clicked). Also you always need to click them to open the menu.

It seems weird to me that the popup menus are basically sub-windows. I mean, uncofusing editor on menu open... I don't know any other application that does that.

[dalexeev]

See also discussion in #37709.

[giarve]

Turns out in X11 the problem is #37709 but not this one #37531.

What I mean is, popup when in front of the editor propagates the hover to editor menus correctly and allows to move through the popup hovering too, which I suppose is the correct behavior (if I understood correctly).

This image was taken using Spectacle with the Capture Mode "Window Under the Cursor" without "Capture the current pop-up only" disabled. If I enable the capture pop-up setting it would only take a screenshot of the dropdown. It seems it is working correctly in linux.

However, the title bar is not in focus, which is what #37709 describes.

Another thing I noticed is that these menus that open on the right of the dropdown when hovering an item with an arrow are not automatically closed when something else is hovered (unlike in dropdown menus in Konsole, which close when the focus is out of the submenu) but this may be another issue and I don't know if it worked like that in Godot 3.2 or not.

[HaSa1002]

In 3.2 Popups close only if you click outside the popup. The Submenus close on hover change

[HaSa1002]

Regarding the blinking issue (and or the focus bug) how are popups handled in X11? On Windows every (native) control is it's own subwindow (as far as I understand)

[akien-mga]

Fixed by #58490.