Hi all,
I had a look at the issues of KRunner on Wayland with Qt 5.9 and want to
share my findings.
What we see is KRunner working fine on first invokation, but afterwards
everything is messed up:
* maximized windows shortly change their size
* KRunner opens behind other windows
With WAYLAND_DEBUG I was able to understand the issue. On first
invokation everything is normal:
* Plasma shell surface gets created
* Plasma shell surface gets positioned
* Plasma shell surface gets marked as panel
* Panel is set to windows go below
* Panel is marked as accepts focus
* Surface gets mapped
Yay, a situation KWin can handle.
Now the window gets hidden, and shown again and Qt recreates the
surface. Due to queuing we have
1. Surface gets mapped
2. KWin shows the window at random position
3. Plasma shell surface gets created and marked as panel
4. KWin adjust it to be a panel and moves maximized windows around
5. Plasma shell surface gets marked as panel with windows go below
6. KWin adjust it to be a panel with windows go below and moves
maximized windows around
7. Panel gets marked as accepts focus (too late, too late)
8. KRunner gets positioned
So we are in a bad state. When looking at it our Plasma Shell Surface
protocol is not double buffered which explains why KWin reacts on each
and every of the actions. It was designed so that double buffered is not
needed as it was supposed to be used before mapping the window.
Now with Qt's new behavior that bites our ass and I'm a little bit lost
what to do. I think we can improve the situation by first setting the
panel behavior, but the wrong position is something we cannot prevent if
the window is already mapped. Even changing the protocol to be double
buffered would not really help here as we are too late. It's not every
frame is perfect.
Any ideas or advice?
Cheers
Martin
Problematic area from WAYLAND_DEBUG:
[2554538,395] -> wl_surface@135.attach(wl_buffer@156, 0, 0)
[2554538,411] -> wl_surface@135.damage(0, 0, 2147483647, 2147483647)
[2554538,677] -> wl_surface@135.commit()
[2554538,793] -> org_kde_plasma_surface@109.set_role(2)
[2554538,807] -> org_kde_plasma_surface@109.set_panel_behavior(4)
[2554538,816] -> org_kde_plasma_surface@109.set_panel_takes_focus(1)
[2554538,855] -> org_kde_kwin_slide_manager@34.create(new id
org_kde_kwin_slide@157, wl_surface@135)
[2554538,871] -> org_kde_kwin_slide@157.set_location(1)
[2554538,879] -> org_kde_kwin_slide@157.set_offset(0)
[2554538,886] -> org_kde_kwin_slide@157.commit()
[2554538,892] -> wl_surface@135.commit()
