(xrandr) scale option freeze screen

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https://bbs.archlinux.org – hello,i have a display pb with the xrandr scale option.in some sessions, when i use it there is no more display: there is a fixed image, only the mouse cursor can move on the screen. this cursor can detect windows borders and other interactive elements (ie: screen elements who should appear but who stay completely masked by the fixed image).So it's more or less like a blank screen, but i can continue to do actions in a blind way.(the pb exists also for the transform and rotate options)example:[guigui@ctkarch ~]$ xrandr --output VGA-1 --scale 0.9x0.9 --verbose(light zoom)the screen become (HowTos)