Fw: Plasma 5.7.5 / 5.8.0 multiscreen: Menu and widgets react to mouse events with seconds of delay if Primary Display = external monitor

[Fredy Neeser]

Hi,

I'm looking for advice on how to narrow down this delay issue, which is
still present in 5.8.1. The delays make my desktop unusable
when I set Primary display = external monitor.

Could this be an unfortunate issue in the interaction between kwin
and XCB/X11 which occurs only if Primary display = external monitor,
or can you think of another potential culprit?

I would like to help debugging the issue -- if necessary, I can try
to build Plasma from sources, but I will likely need some guidance.

Thank you

Fredy Neeser
IBM Zurich Research Laboratory


"Plasma-bugs" <plasma-bugs-bounces at kde.org> wrote on 06.10.2016 14:27:05:

> From: "Fredy Neeser" <nfd at zurich.ibm.com>
> To: plasma-bugs at kde.org
> Date: 06.10.2016 14:27
> Subject: Plasma 5.7.5 / 5.8.0 multiscreen: Menu and widgets react to
> mouse events with seconds of delay if Primary Display = external monitor
> Sent by: "Plasma-bugs" <plasma-bugs-bounces at kde.org>
>
> Hello list
>
> After upgrading from Fedora 22 (Plasma 5.5.5) to Fedora 24 (Plasma
> 5.7.5 and now 5.8.0), I experience a new, multiscreen - related
> mouse-event handling problem, which was not present in Plasma 5.5.5.
> B.t.w., I read about the multiscreen related improvements being
> worked on in 5.7 and 5.8, which I do appreciate.
>
> I'm using a dual-screen setup (LVDS + external monitor), where I
> usually set Primary Display = external monitor. Moreover, I place
> the KDE Panel also on the external monitor. When I do that and try
> to navigate through the Application Menu (launcher with cascading
> popup menus) or when I click / move over a desktop widget, the
> following happens:
>
> - After a mouse left click on the KDE menu icon (left hand side of
> KDE Panel), the menu pops up only after a delay of >= 1 second
> - When the mouse pointer is moved to another item in a popup menu,
> the focus visibly jumps from item to item, and a delay of at least 1
> second is added on every intermediate item.
> - When I click / move over a desktop widget, the desktop reacts with
> a delay of >= 1 second
>
> Note that the delay occurs only for the panel and widgets on the
> external monitor; if I add a second panel and move it manually to
> the laptop screen, the menu on this second panel does NOT have a
> delay problem.
>
> The delay problem on the menu consistently disappears when I set
> Primary display = Laptop Screen, even when the KDE Panel is moved
> manually (via Screen Edge) to the external monitor.
>
> B.t.w., after the recent design changes for multiscreen, it's
> unclear to me in which case a Panel is supposed to move along with
> the Primary display as opposed to being "pinned" to a specific
> display. Could someone please clarify the behavior intended for
> Plasma versions >= 5.7 ? Thanks!
>
> Also, the delay problem typically reappears when I go back to
> Primary display = external monitor. Only in two out of perhaps a
> dozen logout-login cycles, I observed that the delay problem was
> gone, despite the fact that I had Primary display = external
> monitor. This may indicate some kind of race condition at login.
>
>
> Since this was an upgrade from an earlier Plasma version, I also
> tried the following:
> - Remove the contents of ~/.cache
> - Temporarily remove ~/.config, ~/.local and ~/.kde and login to KDE
> - Login to KDE as another user
> but the delay problem behaved the same.
>
>
> The delay problem is exactly the same for Plasma 5.7.5 and 5.8.0:
>
> Plasma 5.7.5 package versions:
> kscreen-5.7.5-1.fc24.x86_64
> kwin-5.7.5-1.fc24.x86_64
> plasma-desktop-5.7.5-1.fc24.x86_64
> plasma-systemsettings-5.7.5-1.fc24.x86_64
> plasma-workspace-5.7.5-2.fc24.x86_64
> plasma-workspace-libs-5.7.5-2.fc24.x86_64
> qt5-qtbase-5.6.1-3.fc24.x86_64
> Plasma 5.8.0 package versions:
> kscreen-5.8.0-0.1.fc24.x86_64
> kwin-5.8.0-0.1.fc24.x86_64
> plasma-workspace-5.8.0-0.1.fc24.x86_64
> plasma-workspace-libs-5.8.0-0.1.fc24.x86_64
> qt5-qtbase-5.6.1-3.fc24.x86_64
>
>
> Please advise on how to best narrow down this issue -- I'd be happy
> to do some testing / debugging!
>
> I tried a KDE Neon Live Image yesterday, but the external monitor,
> although shown by the kscreen control module, turns black after a
> quick initial KDE logo splash at login.
>
> I wish some KDE debug messages could be seen in ~/.xsession-errors
> (I enabled the debug messages using kdebugsettings), but I don't see
> any of the familiar messages - maybe something is broken with the
> KDE debug messages as well.
This problem is now resolved -- debug messages appear in the system log.

> Also, let me know if plasma-bugs is not the right list for this problem.
>
> Thank you!
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