EDIT: I've created a bug report:
https://bugs.freedesktop.org/show_bug.cgi?id=48458
My Setup
I have 4 monitors, 1920x1080, which are in portrait mode (rotated left). They are connected to two radeon graphic cards.
As usual, a picture says more than a thousand words.
The problem
Everything works fine, when Xinerama is disabled. But when I enable Xinerama, things get weird. When I move the mouse of the screen and return, the screen contents begin to move with the mouse, only on this monitor. It seems like the virtual display size does not match the real screen size, which activates a panning viewport. Any idea how to stop this?
The video
I created a video to demonstrate the issue: http://www.youtube.com/watch?v=zq_XHji1P24
xorg.conf
This is my xorg.conf:
Section "ServerLayout"
##################[ Evilness begins here ]#############
Option "Xinerama" "on" # <--- Makes it go b0rked!
##################[ End of all evil ]#############
Identifier "BOFH Console of Doom"
Screen 0 "Screen-0" 0 0
Screen 1 "Screen-1" RightOf "Screen-0"
Screen 2 "Screen-2" RightOf "Screen-1"
Screen 3 "Screen-3" RightOf "Screen-2"
EndSection
Section "ServerFlags"
Option "RandR" "false"
EndSection
Section "Module"
Load "dbe"
Load "dri"
Load "extmod"
Load "dri2"
Load "record"
Load "glx"
EndSection
Section "Monitor"
Identifier "Monitor-0"
Option "Rotate" "left"
EndSection
Section "Monitor"
Identifier "Monitor-1"
Option "Rotate" "left"
EndSection
Section "Monitor"
Identifier "Monitor-2"
Option "Rotate" "left"
EndSection
Section "Monitor"
Identifier "Monitor-3"
Option "Rotate" "left"
EndSection
Section "Device"
Identifier "Radeon-0-0"
Driver "radeon"
BusID "PCI:9:0:0"
Option "ZaphodHeads" "DVI-0"
Screen 0
EndSection
Section "Device"
Identifier "Radeon-0-1"
Driver "radeon"
BusID "PCI:9:0:0"
Option "ZaphodHeads" "DVI-1"
Screen 1
EndSection
Section "Device"
Identifier "Radeon-1-0"
Driver "radeon"
BusID "PCI:4:0:0"
Option "ZaphodHeads" "DVI-2"
Screen 0
EndSection
Section "Device"
Identifier "Radeon-1-1"
Driver "radeon"
BusID "PCI:4:0:0"
Option "ZaphodHeads" "DVI-3"
Screen 1
EndSection
Section "Screen"
Identifier "Screen-0"
Device "Radeon-0-0"
Monitor "Monitor-0"
DefaultDepth 24
SubSection "Display"
Viewport 0 0
Depth 24
EndSubSection
EndSection
Section "Screen"
Identifier "Screen-1"
Device "Radeon-0-1"
Monitor "Monitor-1"
DefaultDepth 24
SubSection "Display"
Viewport 0 0
Depth 24
EndSubSection
EndSection
Section "Screen"
Identifier "Screen-2"
Device "Radeon-1-0"
Monitor "Monitor-2"
DefaultDepth 24
SubSection "Display"
Viewport 0 0
Depth 24
EndSubSection
EndSection
Section "Screen"
Identifier "Screen-3"
Device "Radeon-1-1"
Monitor "Monitor-3"
DefaultDepth 24
SubSection "Display"
Viewport 0 0
Depth 24
EndSubSection
EndSection