Bug 499247

Summary:	On X11, some hover events on apps' UI elements can get broken and stuck in this state
Product:	[Plasma] kwin	Reporter:	Porkepix <porkepix>
Component:	general	Assignee:	KWin default assignee <kwin-bugs-null>
Status:	RESOLVED DOWNSTREAM
Severity:	normal	CC:	kde, nate
Priority:	NOR
Version First Reported In:	6.2.5
Target Milestone:	---
Platform:	Other
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description Porkepix 2025-01-28 16:36:25 UTC

SUMMARY

Issue was noticed when running Fractal, the Matrix client, and appears only in Plasma under a X11 session.

The zone where channel's topic appears normally have a hover event changing background color to a lighter color. However, when "grabbing" the window from that place to move it or to resize it against screen's edge to take half a screen, the hover event becomes broken and it stays permanently in the hover state, as if I was hovering it permanently even when I don't.

As mentioned above, only Plasma under X11 is affected where I could reliably reproduce the issue. I was unable to reproduce the issue on:
- Plasma under Wayland;
- GNOME under both X11 and Wayland;
- XFCE under X11.

STEPS TO REPRODUCE
1. Install Fractal
2. Open a Plasma X11 session
3. Connect to your Matrix account to have any random channel/discussion opened
4. When in one of those places with a "topic", grab the window by the topic place and move it against a screen's edge to resize window on half the screen surface
5. Move it back to windowed/full screen: the topic is now broken and stuck in the hover state.

OBSERVED RESULT

Topic's widget is stuck in a hover state

EXPECTED RESULT

This kind of stuck shouldn't happen.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: ArchLinux
KDE Plasma Version: 6.2.5
KDE Frameworks Version: 6.2.5
Qt Version: 6.8.1

ADDITIONAL INFORMATION

Comment 1 Nate Graham 2025-01-28 17:36:57 UTC

Fractal isn't a KDE app, and on X11, input is handled by the X server, not KWin where we have some control over it. As such, this can't be a KDE bug.

Comment 2 Porkepix 2025-01-28 17:43:06 UTC

(In reply to Nate Graham from comment #1)
> Fractal isn't a KDE app, and on X11, input is handled by the X server, not
> KWin where we have some control over it. As such, this can't be a KDE bug.

Ok but then, where does this issue belong and should be reported? I already talked about the issue with Fractal's people, we were unsure if I should report here or in the toolkit's bugtracker. From what you tell me here, this might be on X11's?

Because for now issue appears only on Plasma's X11, GNOME or XFCE's X11 are not affected by this bug, so could you guide as to where the issue should be reported next according to you please?

Comment 3 Nate Graham 2025-01-28 18:03:39 UTC

To be completely and brutally honest, since it's an X11-only bug, I don't know or care. Development is pretty much Wayland-only at this point. If it works on Wayland, there's basically no chance anyone is going to care; not just me, but everyone either either.

I suspect the issue is in how the toolkit (GTK) interacts with KWin on X11, but I'm pretty sure the GTK devs won't care about this use case either.

It's a wayland world, my friend! I'd recommend trying to move over to it full-time, and if you can't, report the bugs you encounter as a result of the experience, since those are bugs that we're all interested in fixing. If they're significant enough, I'll add them to https://community.kde.org/Plasma/Wayland_Known_Significant_Issues.

Comment 4 Porkepix 2025-01-28 18:19:52 UTC

(In reply to Nate Graham from comment #3)
> To be completely and brutally honest, since it's an X11-only bug, I don't
> know or care. Development is pretty much Wayland-only at this point. If it
> works on Wayland, there's basically no chance anyone is going to care; not
> just me, but everyone either either.
> 
> I suspect the issue is in how the toolkit (GTK) interacts with KWin on X11,
> but I'm pretty sure the GTK devs won't care about this use case either.
> 
> It's a wayland world, my friend! I'd recommend trying to move over to it
> full-time, and if you can't, report the bugs you encounter as a result of
> the experience, since those are bugs that we're all interested in fixing. If
> they're significant enough, I'll add them to
> https://community.kde.org/Plasma/Wayland_Known_Significant_Issues.

I know, and use Wayland sessions most of the time (although most of my time isn't spent on KDE), but sometimes various reasons can make you prefer the X11 counterpart (such as bugs on icons, not breaking bugs, bug very annoying for daily use), even if you lose nice things (multitouch navigation in Firefox, for example, is neat, and Wayland-exclusive). Some DEs/WMs also are quite late for their Wayland support/migration (XFCE, LXDE), or even don't plan on ever doing one (i3wm, Awesome WM and so on) while still having users :)

For my personal case, although I spent more time on GNOME and Hyprland, for now the icons issues are irritating enough that I'd prefer to run Plasma over a X11 session though.

Anyway, I'd usually report an issue I find even if, because maintainer don't have the time to tackle it (issue's too minor, is about abandoned features like X11 support might be here, nobody's interested into working on this issue, because no maintainer ever owe anything to anyone, or whatever reason maintainers could have), but from what I understand and regarding KDE specifically, if I find new issues that affect Plasma only on X11 session while being fine on Wayland, then it's better not to report them anymore, right?

Comment 5 Nate Graham 2025-01-30 16:59:54 UTC

No no, I'm not saying never report X11-specific issues; that's still fine in a general sense. I guess what I'm saying is be prepared for them to get closed without being fixed if developers judge them to be too niche or time-consuming to be worth fixing. Basically, manage your expectations regarding bug fixes for issues specific to the Plasma X11 session.