r_fullscreen does not spread on all screen

seta r_customheight "1080"
seta r_customwidth "1920"
seta r_mode "-1"
set r_customaspect "1"

Yes but the higher is the resolution and the lower are the FPS.

depends on whether you use nvidia control center or ccc,

select a valid resolution such as

800x600
1024x768
1280x1024
1280x960
1440x900
1600x900
1366x768
1920x1080
1440x1080
2560x1560

and so on

then once you selected it for your desktop, choose automatic scaling over the whole monitor

once you did that you are able to set your desktop resolution back to native, but every time you run that resolution in a game, it should automatically stretch it - but make sure you set exactly the same resolution as you did on the desktop during the moment you changed the scaling option, else it won't work

if you don't the r_mode for your resolution simply set
r_mode -1
r_customheight ""
r_customwidth""

Well but i whish i play with r_mode 4 so i have more FPS...

Thank you all.