'Fullscreen - Browser' startup mode - Browser in front

[ManiaXX]

Hallo,
when i double-click a picture in OS file browser (Thunar/XFCE) XnViewMP v0.87 shows the picture in fullscreen properly but also overlays the XnViewMP browser and the OS taskbar to the front. I always have to click somewhere in the fullscreen area to get both to the background. I've especially selected 'Fullscreen - Browser' startup mode because i want to get into 'Browser' when double-clicking fullscreen area.

Can you add an option to make the 'Fullscreen' mode to be always on top?

Arch Linux 4.12.10 x86_64
XFCE/GTK+
aur/xnviewmp-system-libs 0.87-1 (08 Sep 2017)

[xnview]

i'll check if it's a problem with QT libraries