LMMS
Window border flickers on dragging
Bug Summary
When dragging any in-app window, the border on the side towards drag direction starts to flicker.
Screenshot
Affected LMMS versions
1.2.1
OS Version: KDE Neon 5.19
Logs
Click to expand
Can you see if this happens with other Qt apps? I'm not sure if you'll be able to find one that uses MDI like we do, so this may be a rather impossible request, but on a 4K display, I don't see the same flickering (1.2.2, macOS) meaning that it's likely to be a fault of the Qt framework.
@tresf Just tried several another Qt apps, and didn't see any similar issue.
They'd probably need to be using MDI windowing components, which most apps have ditched. I'm just not sure it's something LMMS can patch. It's likely an aliasing problem with certain Desktops/graphics subsystems with the 1px window border used for the MdiSubwindow class. If this theory is correct, reverting to the legacy theme will probably help mask it.
But it's not LMMS' job to compensate for misdrawn windows, so unless it's a bug introduced with our code or theme, the best we can do is attempt to mask the issue by tweaking the theme. Even then it may end up won't-fix, the windowing will all be changed when single-window is live and these types of bugs would be less likely to be observed.
I think this is a general artifact of global scaling especially under X11. I have also experienced this with a scaling of 1.25. It's somewhat better under Wayland.
