When I exit from low resolution fullscreen games/apps, the desktop icon positions change to fit in the low-res limits. I tried to workaround that by changing the owner and permissions of ~/.config/xfce4/desktop/icons.screen0.rc, but they're always changed automatically back and the file is rewritten. 
I workarounded that by script copying a backup of my icons to ~/.config/xfce4/desktop/icons.screen0.rc, but even if I let it run automatically, a manual refresh of the desktop (with F5 key) is always needed. 

It would be nice to let the file untouched until the position of icons is set manually. If the icon position is outer the screen limits, then a new temporary position should be calculated (but without writing in the .rc file). And once the resolution is changed back, the .rc file should be reread and the icons put back on their original positions.