Bug 494702

Summary:	Mouse flickers and can get stuck grabbing dragged items/prevent showing auto-hidden panel when InputCapture portal is repeatedly activated and deactivated quickly
Product:	[Plasma] kwin	Reporter:	gabe <cheery.idea2032>
Component:	wayland-generic	Assignee:	KWin default assignee <kwin-bugs-null>
Status:	RESOLVED DOWNSTREAM
Severity:	normal	CC:	aleixpol, cheery.idea2032, kde
Priority:	NOR
Version:	6.2.0
Target Milestone:	---
Platform:	Fedora RPMs
OS:	Linux
Latest Commit:		Version Fixed In:
Sentry Crash Report:

Description gabe 2024-10-13 22:57:23 UTC

SUMMARY
When using an app like Deskflow, pressing the mouse against an edge with no client on the other side will generate a bunch of portal activations and deactivations, which appears to make the mouse flicker and can unwanted behavior, such as dragged items getting stuck on the mouse after letting go during this flickering, or the auto-hiding panel not appearing when pressing the mouse against the bottom edge of the screen.

STEPS TO REPRODUCE
1. Launch Deskflow (with Debug1 logs to see the libei information) and no clients configured
2. Press mouse against bottom edge of screen

OBSERVED RESULT
Mouse flickers, and the auto-hiding panel does not appear

EXPECTED RESULT
No mouse flickering, and the auto-hiding panel appears

SOFTWARE/OS VERSIONS
Operating System: Fedora Linux 40
KDE Plasma Version: 6.2.0
KDE Frameworks Version: 6.7.0
Qt Version: 6.7.2
Kernel Version: 6.10.12-200.fc40.x86_64 (64-bit)
Graphics Platform: Wayland
Processors: 16 × AMD Ryzen 7 5700X 8-Core Processor
Memory: 31.2 GiB of RAM

ADDITIONAL INFORMATION
Original bug report: https://github.com/deskflow/deskflow/issues/7632

Comment 1 gabe 2024-10-13 23:05:21 UTC

I can actually get the portal to deactivate and reactivate repeatedly, causing the mouse to flicker, by slowly moving my mouse between two monitors that are both connected to the InputCapture "server". Even though the mouse isn't moving to an edge boundary of the server, just moving between its own monitor layout.

Comment 2 David Redondo 2025-01-13 09:04:50 UTC

> 1. Launch Deskflow (with Debug1 logs to see the libei information) and no clients configured
> 2. Press mouse against bottom edge of screen

Deskflow should not configure a barrier in this case. KWin can't know what a client wants to do with the input capture