I have an internal LVDS (1280x800) and an external DVI (1280x1024). The laptop's lid is closed, and the laptop is docked, so I don't care about the LVDS at all. KMS sets up both outputs correctly:

[ 2.326217] [drm] TMDS-13: set mode 1280x1024 27
[ 2.590106] [drm] LVDS-8: set mode 1280x800 28

A few weeks ago, when I started using KMS, all was well: The X server detected that the kernel already set the mode, and continued to use 1280x1024 on my external DVI screen. gdm appeared in full resolution, and there was no mode switch between kernel, gdm, and GNOME.

In GNOME's xrandr configuration I switched off LVDS and just use DVI. In gdm (with no custom xrandr), the LVDS is active, and I guess at those times it just showed 1280x800 and cut off the lower portion of the screen.

However, nowadays the X server tries to be too clever, and chooses 1024x768:

(II) intel(0): Output LVDS1 using initial mode 1024x768
(II) intel(0): Output DVI1 using initial mode 1024x768

This has several nasty effects:

 * This mode is non-native to neither of the outputs, so both look ugly
 * It reintroduces mode switches (kernel -> X.org startup and gdm -> GNOME session)

In my ideal world, X.org would see that my laptop's lid is closed and just shut off LVDS and use DVI only by default (i. e. what I set in my xrandr configuration). In theory, X.org can access this information, either from the kernel or from devicekit-power:

$ devkit-power --dump|grep lid
  lid-is-closed: yes

If that's too complicated, then maybe it could default to only using the external, or only using the device with the largest resolution available, and switch off the others? If you need them, you can still configure them with xrandr, but IMHO the current default isn't very good.

I'll attach my Xorg log. If you need further data about my hw, it's all attached to the linked Ubuntu bug. E. g.

  dmesg: http://launchpadlibrarian.net/28597000/BootDmesg.txt
  xrandr: http://launchpadlibrarian.net/28597013/Xrandr.txt

Software environment:
  Linux 2.6.31rc1 (happend on 2.6.30, too)
  X server 1.6.1.902 (git from 2009-06-29)