xrandr with Xinerama and BOTH nvidia and ATI card

[funknor]

Has anyone successfully configured two graphic cards (nvidia & ATI) that xrandr works in a multiple head environment? I would like to get some of the GLX libs to work, but after trying so many different driver combiniations, the only one that work is native nvidia (nv) and radeon.

Background, I have a tripple head configuration, one monitor is connected to an nvidia card, the other two are connected to an ATI card. Tripple head works great, but I don't get 3d graphics acceleration to work. Here are the relevant videocard entries:
Section "ServerLayout"

# Screen 1 "Screen1" Relative "Screen0" 1024 0
Identifier "Multihead layout"
Screen 0 "Screen0" 0 0
Screen 1 "Screen1" RightOf "Screen0"
Screen 2 "Screen2" RightOf "Screen1"
InputDevice "Keyboard0" "CoreKeyboard"
InputDevice "LogitechMouse" "CorePointer"
InputDevice "BT Mouse" "CorePointer"
Option "Xinerama" "on"
Option "Clone" "off"
EndSection

.....

Section "Device"
Identifier "Videocard0"
Driver "nv"
Option "HWCursor" "off"
EndSection

Section "Device"
Identifier "Videocard1"
Driver "radeon"
Option "MonitorLayout" "TMDS, CRT"
BusID "PCI:1:8:0"
EndSection

Section "Device"
Identifier "Videocard2"
Driver "radeon"
VendorName "Videocard Vendor"
BoardName "ATI Technologies Inc RV280 [Radeon 9200]"
BusID "PCI:1:8:0"
Screen 1
EndSection