intel driver: monitors vs screens

[Michael J. Hammel]

On Mon, 2007-10-22 at 04:38 +0100, Peter Clifton wrote:
> For more information, and for how to set this up in your xorg.conf once
> you've found how you like it, take a look at this guide:
> http://www.intellinuxgraphics.org/dualhead.html

After a bit of experimentation (mostly based on lessons learned with the
i810 driver) I've got this working on my laptop (Acer Aspire 1691WLMi,
w/ i915GM).  But it doesn't seem to work exactly as I'd like, or as it
worked with the old i810 driver.

The 915 is limited to the 2048x2048 dimensions with this chipset, so my
external monitor is positioned using xrandr above the LCD monitor since
there is vertical space but no horizontal space in that 2048x2048 block
for the external monitor.  That works fine.  If I set the external
monitor to a resolution different than the LCD then the GNOME desktop on
the LCD is changed to fit the new size.  For example, if I set the LCD
to 1280x800 and the external to 1024x768, GNOME's desktop on the LCD
shrinks horizontally and veritically on the LCD.  If I make the external
1280x768 then only the vertical shrinks.  This is mostly just annoying -
the panel at the bottom of the display doesn't hide because it's higher
than the physical location it started at when only the LCD is
configured, or the panel at the top of the display shrinks and
rearranges the icons in the panel.

I'd expect this to be a GNOME issue, but then I found two other things.
The first is that starting MythTV with Xinerma enabled and using Screen
1 has no effect.  When started, MythTV always starts on the LCD.  I
can't get it on the external monitor, though this did work with the
proper Screen configurations with the i810 driver.  Note that the
intellinuxgraphics/dualhead.html page doesn't mention use of the Xinerma
option as it was used with the i810, so at this point I've not enabled
Xinerma in the xorg.conf.

But then I noticed that OpenOffice *does* pick the external monitor if I
tell it to.  But it's configuration mentions "monitor" and not "screen".

So I'm wondering if the dualhead.html description is actually setting up
logical X screens such as what MythTV is looking for.  Or is it using a
physical monitors on a single logical screen?  If the former, is this a
change that applications should be made aware of - using "monitors"
instead of logical "screens"?

-- 
Michael J. Hammel <xorg at graphics-muse.org>