Comment 23 for bug 302227

Created an attachment (id=25621)
Xorg.0.log

Forwarding this bug from a Ubuntu reporter:
https://bugs.edge.launchpad.net/ubuntu/+source/xserver-xorg-video-intel/+bug/302227

[Problem]
On dual-head setup, mouse cursor movement is restricted to a 800x600 window unless dragging; outside this area redraw in compiz is affected as well.

[Discussion]
First shown with Compiz enabled on a two-screen netbook (Acer Aspire One, external 1024x768 screen to the right of built-in LCD) setup. Anything past the leftmost 800x600 would not be erased after being drawn and external monitor resolution would be misdetected.

Upon disabling Compiz, things are properly erased, but after login the pointer is restricted to the leftmost 800x600 rectangle and I need to drag something outside the rectangle to be able to move the pointer freely.

Since the redraw vestiges happen only outside an 800x600 window (the same size the greeter used), it is possible that the background window (or however it may be called in Z/Compiz-speak) responsible for ensuring things get erased when needed is being sized at the same size the greeter used (800x600 in this case) instead of the size of the combined monitor area (2048x768).

- Can't drag mouse outside leftmost 800x600 region
- Can't drag icons outside leftmost 800x600 region
- Screenshots only grab the leftmost 800x600 rectangle (so I can't show most of what I am experiencing)
- Right-clicking icons in the top Gnome bar makes the pop-up menu appear in the leftmost position of the external monitor

One more comment: X/Compiz work fine on the LCD-only configuration. The 800x600 rectangle the cursor is confined to in the double-headed config is notable because it's the same resolution that the GDM takes (probably because it's the largest VESA-like mode both monitors can show).

I had the opportunity to hook up the laptop to a couple odd monitors (I have a collection of "interesting computers" and recently got a couple Intergraph behemoths with coax and DB-15 connections). All were misdetected and the same rendering and pointer confinement anomalies happened.

The problem is present in Jaunty. Using xserver-xorg-video-intel 2:2.6.3-0ubuntu9 and compiz 1:0.8.2-0ubuntu8, more or less the same dual-monitor oddness persists. The difference is the login screen is not squashed in the built-in widescreen display, but is 800x600 on the secondary (still misdetected) monitor. Desktop background and mouse movement are still limited to the top-left 800x600 rectangle of the multi-head desktop until I drag the mouse. Windows are still not properly erased outside the top-left 800x600 region.

Oddly enough, the problem vanished when I started the computer with the second monitor plugged in but turned off this morning and rearranged the dual-screen config with the screen applet. X still but started with mirrored screens at 800x600.

[lspci]
00:00.0 Host bridge [0600]: Intel Corporation Mobile 945GME Express Memory Controller Hub [8086:27ac] (rev 03)
 Subsystem: Acer Incorporated [ALI] Device [1025:015b]
00:02.0 VGA compatible controller [0300]: Intel Corporation Mobile 945GME Express Integrated Graphics Controller [8086:27ae] (rev 03)
 Subsystem: Acer Incorporated [ALI] Device [1025:015b]

[xorg.conf]
Section "Screen"
 Identifier "Configured Screen Device"
 Device "Configured Video Device"
 SubSection "Display"
  Virtual 2048 768
 EndSubSection
EndSection

Section "Device"
 Identifier "Configured Video Device"
EndSection