For a few versions now (maybe ever since 7.5.x, I don't remember, and rolling back too far is likely untenable due to complex dependencies), my scroll-wheel hasn't worked in libreoffice when USE="gtk" is set. I haven't noticed this in any other apps; for testing, I set USE="gtk" and installed x11-terms/mlterm and net-irc/hexchat and the mouse wheel worked fine in them. If I disable USE=-gtk and rebuild, scroll-wheel works fine again. I'm using fvwm-crystal with sloppy focus enabled. Can't try libreoffice-bin at the moment because it only supports python3_11 and I haven't finished moving some packages in my internal overlay up from 3_10 yet.
Additional data point: reproduced with both x11-libs/gtk+-3.24.35 and x11-libs/gtk+-3.24.38
Still having this issue with app-office/libreoffice-7.5.9.2
Firefox with MOZ_USE_XINPUT2!=0 behaves similarly, with fingers pointing at GTK3, and so I wonder if these are related (except libreoffice has no such knob).
Rebuilt with USE=gtk and the workaround of GDK_CORE_DEVICE_EVENTS=1 helps. Libreoffice apps feel sluggish to respond to the mouse scrollwheel but I don't have any hard data for that; at least it works at all.
