As described in the KDE forum (https://forum.kde.org/viewtopic.php?t=141296):
I've recently upgraded to Plasma 5.10.4 and I'm having an incredibly annoying issue. Occasionally, ALT-TAB is ignored the first 1, 2 up to 5 or so times, and then it finally works. This is unacceptable because when I'm programming / debugging / testing I have to switch windows and do a lot of different things and I don't have time to wait for visual confirmation that my keyboard command was acknowledged. I just send keystrokes to my hands and expect the computer to work, but end up typing into the wrong window because of this.
Proposed patch to fix: https://phabricator.kde.org/D13128
Git commit 706730f9d7a3357c703d5a24833f0436972b1b91 by Elvis Angelaccio, on behalf of Sontol Bonggol.
Committed on 01/06/2018 at 21:44.
Pushed by elvisangelaccio into branch 'master'.
Make sure ungrab keyboard request is processed before emitting shortcut
In some rare cases, the ungrab keyboard request is processed later than
the action of the key shortcut. This can make the application that try
to grab the keyboard (e.g. in kwin) fail to do so. The solution is to
use ungrab_keyboard_checked() and xcb_request_check() before emitting
the shortcut signal.
Reviewers: #frameworks, #plasma, mck182, davidedmundson
Reviewed By: #plasma, davidedmundson
Subscribers: elvisangelaccio, davidedmundson, fvogt, kde-frameworks-devel
Differential Revision: https://phabricator.kde.org/D13128
M +5 -1 src/runtime/plugins/xcb/kglobalaccel_x11.cpp
*** Bug 392302 has been marked as a duplicate of this bug. ***
*** Bug 395165 has been marked as a duplicate of this bug. ***
*** Bug 391056 has been marked as a duplicate of this bug. ***