Send Mouse Enter/Exit Notifications independently of mouse focus

[Sauermann]

Previously, the mouse focus (Viewport::gui.mouse_focus) influenced, when NOTIFICATION_MOUSE_ENTER and NOTIFICATION_MOUSE_EXIT are sent.
This patch changes the behavior, so that only the mouse position, but not the mouse focus has an effect on when the two notifications are sent.

resolve #19808
related to #20881
related to #32943
related to #54565

[RandomShaper]

At line 1611 (and maybe at some other spots) there's logic similar to the one modified in this PR, this time for the case of mouse exit. Wouldn't it need some changes, too?

[Sauermann]

@RandomShaper Thank you for pointing me to this code section.

The code around line 1611 is responsible for sending EXIT notifications after a DragAndDrop LBM-release. Since EXIT notifications are now handled solely by mouse position, that code at line 1611 can be safely removed, since it is redundant (it would trigger only after the node already has lost focus).

I searched and found no other locations with similar logic.

[Sauermann]

It would be good, if someone with knowledge about mouse capture mode can have a look at this.

[RandomShaper]

It would be good, if someone with knowledge about mouse capture mode can have a look at this.

Any specific concern regarding capture?

[Sauermann]

I was concerned, that MOUSE_MODE_CAPTURED might interfere with this change in unexpected ways based on this comment: #20881 (comment)

I made a few tests and since in that mode the mouse cursor is always kept in the same place, it behaves as I would expect regarding Enter/Exit Notifications.

[RandomShaper]

As far as I can tell, this is good to to. Let's have it in the back of our minds in case something weird with mouse enter/exit happens, though.

[akien-mga]

Thanks!