Bug 378532

Summary:	fast window switching (ALT+Tab) is broken for fullscreen windows
Product:	[Plasma] kwin	Reporter:	FabiB <plusfabi>
Component:	general	Assignee:	KWin default assignee <kwin-bugs-null>
Status:	RESOLVED NOT A BUG
Severity:	normal
Priority:	NOR
Version First Reported In:	5.9.4
Target Milestone:	---
Platform:	Other
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description FabiB 2017-04-07 11:26:04 UTC

KDE Frameworks 5.32.0
Qt 5.8.0 (built against 5.8.0)
The xcb windowing system
(also on Wayland)

Open a few windows, now you can "fast switch" between 2 windows via ALT+Tab. That works good and many use it. Now when you open a game (Stardew Valles, Tomb Raider, RocketLeague and all other games i have in Steam) and its launched fullscreen, fast user switch will not work anymore.

Start the game -> game opens
ALT+Tab switches out of the game
another ALT+Tab will NOT switch back to the game, but a random other window. It seems this only affects OpenGL and Vulkan windows. If i run Chromium with F11 in fullscreen an can switch just fine in and out.

If I start the game in windowed-mode, fastswitch also works fine.

If you need more infos - please let me know :)

Comment 1 Martin Flöser 2017-04-07 12:52:03 UTC

might it be that the window closes when losing focus?

Comment 2 FabiB 2017-04-07 23:33:40 UTC

(In reply to Martin Gräßlin from comment #1)
> might it be that the window closes when losing focus?

It only gets minimized when it loses fokus.

Comment 3 Martin Flöser 2017-04-08 05:52:54 UTC

(In reply to FabiB from comment #2)
> (In reply to Martin Gräßlin from comment #1)
> > might it be that the window closes when losing focus?
> 
> It only gets minimized when it loses fokus.

Minimized windows are moved to the last position in window switching. This is clearly a bug in the games. There is no reason to minimize and that is not the expected behavior.

Comment 4 FabiB 2017-04-08 11:14:16 UTC

I dont think it's a bug but a design choice for all kinds open OpenGL,DirectX,Vulkan Applications when they run fullscreen and lose the focus. Not on Linux, but a real standard behavior.

Note: this is for "real fullscreen", not "borderless maximized".

SDL, for example, has a switch for this to run off because it's a default setting
SDL_VIDEO_MINIMIZE_ON_FOCUS_LOSS=1

----

But now as you mention it: why is the minimized window put to the end of the list, thats (for me) really unexpected and feels strange

Comment 5 Martin Flöser 2017-04-09 07:53:04 UTC

> why is the minimized window put to the end of the list, thats (for me) really unexpected and feels strange

I have no idea it has been like that before I joined development.

Comment 6 FabiB 2017-04-16 18:32:53 UTC

Is there maybe some kind of kwin rule to completely disable that minimized windows are going to the end of the list? It really bothers me much, since I know it.
Thats also the reason why my the window switcher (when you press and hold ALT+Tab) is so jumpy when placing windows. I though for the last few years that kwin got confised when Compositing got switched off and on and thats why windows often appear in a completely new order, but its really because minimized windows are switching to the last place on the list.

Comment 7 Martin Flöser 2017-04-17 07:36:56 UTC

(In reply to FabiB from comment #6)
> Is there maybe some kind of kwin rule to completely disable that minimized
> windows are going to the end of the list? It really bothers me much, since I
> know it.

As far as I have seen the code there is no way to influence this at all.