Re: first display on twinview
The UseDisplayDevice seems to only solve part of the problem. It works when what is wanted is to enable only one or several particular monitors (that are not CRTs for example).
But if what you want is enable two monitors (DFP-0 and a CRT-0) on the same card, and make DFP-0 the primary monitor on the Xinerama extension, this still doesn't work (ie gdm will still appear on the CRT screen, instead of the DFP).
For example, I used the option "UseDisplayDevice" "DFP-0, CRT-0" in my config file, but the log of the X server shows that devices have been reordered "CRT-0, DFP-0", and gdm appears on the CRT.
Am I missing something?