Xrandr 2 écrans - portrait - paysage

bonsoir

debian 8 - mate - ATI Radeon X1600/X1650 Series

moniteur acer 16/9 en position portrait = DVI-0
moniteur philips 4/3 = DVI-1

:~$ xrandr

Screen 0: minimum 320 x 200, current 2720 x 1024, maximum 8192 x 8192
DVI-0 connected 1440x900+0+124 (normal left inverted right x axis y axis) 410mm x 257mm
1280x1024 75.02 60.02
1440x900 74.98* 60.07
S-video disconnected (normal left inverted right x axis y axis)
DVI-1 connected 1280x1024+1440+0 (normal left inverted right x axis y axis) 376mm x 301mm
1280x1024 60.02 + 75.02*
1280x960 60.00

je veux le moniteur acer 16/9 en affichage portrait

:~$ xrandr --verbose --output DVI-0 --rotate right
screen 0: 2720x1564 719x413 mm 95.98dpi
crtc 0: 1440x900 74.98 +0+124 “DVI-0”

seul le curseur de la souris a bien basculer en mode portrait mais pas le bureau

:~$ xrandr
Screen 0: minimum 320 x 200, current 2720 x 1564, maximum 8192 x 8192
DVI-0 connected 900x1440+0+124 right (normal left inverted right x axis y axis) 410mm x 257mm
1280x1024 75.02 60.02
1440x900 74.98* 60.07
S-video disconnected (normal left inverted right x axis y axis)
DVI-1 connected 1280x1024+1440+0 (normal left inverted right x axis y axis) 376mm x 301mm
1280x1024 60.02 + 75.02*
1280x960 60.00

merci pour votre aide