Waveform splitter broken with Wayland and QOpenGL

[aladar42]

Bug Description

I am assuming this is a new bug, as I have been using Mixxx for two years on this same install and never encountered this.

When I tried resizing the elements to make the waveform window a little smaller, I found out dragging to resize doesn't work - the UI moved a few pixels, and then got stuck. Figuring that I'll just work around the bigger waveform, I have started browsing my library to load a track, and then the UI completely broke as the waveform window resized itself to the point where I can't even see the library. It happened instantly so I assume the software thought I am still holding the mouse button and dragging the resize function. Now I cannot resize the UI at all, nor reset it in any way - the resize function moves the window by a few pixels up, then a few pixels down, and then gets stuck there like that. See attached video.

https://streamable.com/6wd5tc

Running on Arch Linux, KDE Plasma, Wayland, Linux 7.1.5, Qt 6.11.1. Everything in my DE is default, nothing unusual or swapped out.

Version

2.5.6

OS

Arch Linux

[ronso0]

Does dragging down work, just upwards is broken?
If yes, I'm pretty sure this is related to Wayland, see #14492 + #16013

Does it make a difference if you disable Acceleration in the Waveform preferences?

[ronso0]

Also related:
#13414

[aladar42]

Does dragging down work, just upwards is broken? If yes, I'm pretty sure this is related to Wayland, see #14492 + #16013

Does it make a difference if you disable Acceleration in the Waveform preferences?

Turning off acceleration did fix it. This is weird, though, I have been running Wayland since about end of 2024 but encountered this only now, I haven't even encountered the bug in #14492 yet.

I assume there's not much more help I could be, if we know the root cause, then? Thank you for your help.

[ronso0]

Yeah, the root cause is QOpenGL mouse handling in Qt's Wayland backend IIRC
Not sure how to fix this.

This is weird, though, I have been running Wayland since about end of 2024 but encountered this only now, I haven't even encountered the bug in #14492 yet.

Maybe a Qt or Wayland update caused this? Might be worth checking the Wayland / Qt bug trackers.