bug#52686: menus in qt programs not visible or appearing far away on wayland

["bdju" via Bug reports for GNU Guix <bug-guix@gnu.org>]

On Wed Dec 22, 2021 at 5:20 AM CST, Josselin Poiret wrote:
> This seems like those programs are running with the XCB backend, using
> XWayland, rather than directly using Wayland.

`swaymsg -t get_tree` output shows they have an app_id instead of a
class, this is how I'm determining they're using Wayland. They in fact
used to use a class. I am not using the env var to force wayland as it
had issues in the past, but after upgrading packages recently, it seems
they went back to using app_id.

> Could you give us some more information about your system and Wayland
> compositor?

Like I said at the top, I am using Sway as my compositor, on the Guix
System distro. What else would be helpful to know?

> Can you try launching those in a shell using `QT_QPA_PLATFORM=wayland
> pcmanfm-qt` for example after installing qtwayland in your profile?

Looks like I have qtwayland in my profile already.
I experience the same issues after launching pcmanfm-qt with that env
var at the start. The terminal shows this:
8:41:13.012|default|W|QSocketNotifier: Can only be used with threads
started with QThread

> I cannot replicate on Sway 1.6.1 with either the xcb or wayland backends
> of Qt.

Thank you for testing.