global shortcuts and drop-down active

[Lubos Lunak]

On Wednesday 07 of November 2007, Andriy Rysin wrote:
> Hi,
>
> global shortcuts in KDE4 (as well as in KDE3) don't work when drop-down
> (menu or combobox) is active.

 http://bugs.kde.org/show_bug.cgi?id=70063

> E.g. if I start typing something in Dolhpin address bar (or firefox) the
> drop down with choices appear and I try to e.g. switch keyboard layout with
> Ctrl+Alt+K or  enable/disable actions in klipper with Ctrl+Alt+X it does
> not work.
> Is this working "as designed" because of some limitations or it's a bug in
> shortcut handling?

 It is definitely not a bug. When you have a popup, that popup needs to 
receive keyboard events. There are two ways to receive keyboard events, 
either have the focus or grab the keyboard. Since application showing the 
popup not always has focus at the moment (e.g. Klipper and its popup), the 
solution is to grab the keyboard while the popup is visible. Now, since the 
application has the keyboard grabbed, other applications don't get any 
keyboard events, therefore their shortcuts don't work.

 I'm not aware of any other alternatives other than these two. X doesn't seem 
to provide any usable mechanism to somehow handle shortcuts during keyboard 
grab. Which means that even if we find another way, that another way would be 
changing how keyboard handling for popups works, which would require 
cooperation from the application showing the popup and as such it cannot work 
for all apps.

 Even then, I'm not quite sure about how to solve it. If the application 
already has focus (which I assume represents most of the cases), then the 
application itself (toolkit, actually) could just avoid the grab and handle 
routing the input event from the focused toplevel window to the popup itself. 
If you run some application with --nograb then you will get more or less this 
(note, --nograb works only with debug-enabled Qt). It would need few tweaks, 
but this could be a relatively simple solution for most cases including 
dropdowns, although not for all popups.

 Better solution would however require much more work. Regardless whether the 
solution would be making the popup's application somehow forward shortcuts to 
other apps or setting focus to the popup, there would be problems and their 
solving would require creating a widely used spec. Forwarding shortcuts would 
be probably practically unfeasible anyway, with focus setting there would be 
undesired focus changes (indeed) that I don't know how would be difficult to 
handle.

-- 
Lubos Lunak
KDE developer
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