Hi Davy
- Default GTK+ configuration seems to be "non standard" (gtk-theme-name is set to oxygen-gtk and gtk-icon-theme-name is set to oxygen-gtk both in /etc/gtk-2.0/gtkrc/ and /etc/gtk-3.0/settings.ini instead of respectively "Adwaita" and "gnome") causing some glitches (for example, when you change the volume with mutimedia keys, the OSD sound volume background image is missing and replaced by an ugly gray) ;
This (the use of oxygen-gtk) is 'on purpose', to have a consistent look and feel across DE, and across toolkits. Now, there might indeed exist rendering bugs with oxygen-gtk + gnome. They deserve a bug report (so that I can fix them, on the 'upstream' oxygen-gtk side. Either at https://bugs.mageia.org/, or (even better) at bugs.kde.org. Product being oxygen, and component gtk2-engine or gtk3-engine, depending on which is the underlying toolkit. Screenshots also appreciated.
Cheers, Hugo
