Icons are missing in the Xfce menu
From Salix OS
If you installed a new software package and the respective icons are missing from the Xfce menu, it's because Xfce is too slow to update the icon caches. Just run the following command as root to update the icon cache for all icon themes installed in your system:
for i in /usr/share/icons/*;do gtk-update-icon-cache -f $i; done
If you have any icon themes installed in your home directory instead of having them installed systemwide, you probably need to run something similar for them (as non-priviliged user this time):
for i in ~/.icons/*;do gtk-update-icon-cache -f $i; done