Description:
In the current Arch Linux build of shotcut (23.09.29-1), the timeline is completely blank and unusable, and nothing happens when you try to drag a video or audio file to it (it should be added to the timeline). I was able to reproduce this issue on 2 separate computers running up-to-date Arch Linux, with KDE Plasma desktop environment (I have not tested it on other desktop environments or window managers). The official build of shotcut 23.09.29 provided by upstream does not contain this bug. I think it's high severity because the timeline should be considered main functionality of a video editor software, since you can't really do much video editing without using the timeline.

Additional info:
* package version: shotcut 23.09.29-1
* The official build (provided by upstream) of shotcut 23.09.29 uses qt 6.4.3
* The Arch Linux build of shotcut 23.09.29-1 uses qt 6.6.0
* Apparently this isn't the first time this bug happens with the Arch Linux build of shotcut. See this post from Jan 2021:
<https://forum.shotcut.org/t/solved-something-happened-to-my-timeline/24155>, and note that just like this time, the bug also didn't exist in the official upstream build of shotcut, but rather it manifested itself only in the Arch Linux build of shotcut. The author "solved the issue" by ditching the Arch Linux build of shotcut, and using the build provided by upstream (it was posted on the shotcut forum, after all).

Steps to reproduce:
Update Arch Linux, install shotcut with pacman, and verify the timeline is blank, and it's not possible to use it or interact with it in any way (at least on KDE Plasma desktop environment, since that's what I'm using).