It took me about five minutes to get dual monitors working on my Dell Inspiron 1501 under Ubuntu 7.04. Here’s how I did it.

  1. I tried the xorg driver, which had been working fine on just the laptop display, but it wouldn’t work; I could get either the external display or the internal display to show, but not both. If you get it working, post a comment and let me know.
  2. I enabled the proprietary driver via Ubuntu’s Restricted Drivers Manager.
  3. I read the Gentoo Wiki page on dual monitors.
  4. As root, I ran
    aticonfig --initial=dual-head --screen-layout=above -v
  5. I rebooted.

At the moment, I’m typing into Firefox on the laptop monitor. My Dell 1800FP monitor is perched right above it; it’s the same width in pixels, and almost the same physical width. I have no windows open on that monitor, but I do have a nice background image! XFCE configures the backgrounds for each display separately.

I’ve been using this setup for about a week now. It’s not flawless, but the flaws don’t get in my way much. Here are the problems I’ve noticed:

  1. The driver is proprietary. Okay, this is a major flaw.
  2. The driver doesn’t work perfectly. Occasionally a weird defect in the screen image appears and won’t go away until X is restarted. It looks like a bar code and usually shows up near the bottom right of one of the monitors, often right over the clock in my system tray.
  3. If I log out of XFCE, my system hangs and I have to use the Alt-PrntScrn keys to shut it down and restart it.
  4. When I start my laptop, only the display on my laptop shows anything (perhaps the login screen isn’t dual-monitor capable). As soon as I log in, both monitors become active. While this is happening, my mouse randomly jumps between the top-left corner of the two monitors.

The two monitors are running two different X displays. I’m not crystal-clear on how this should normally work, but I get the idea Xinerama isn’t the same as this and should work better (I don’t know if I can set up Xinerama with the proprietary driver, but I don’t think so). This has a variety of side effects:

  1. Windows I open on one display can’t be moved to the other (oddly, I can drag and drop between displays, which I didn’t expect).
  2. I can’t alt-tab to the other display.
  3. When I click on a link in Thunderbird, if Firefox is running on the other display, it says Firefox is already running but not responding, and refuses to open the link. I can’t get Firefox running on both displays at once.
  4. My XFCE panel on the laptop display doesn’t show windows on the other display. I tried creating a panel for that display too (XFCE recognizes that there are two displays and lets me place the panel on either one), but I couldn’t place it at the bottom of the display. When I chose to place it at the bottom, it seemed to place itself 768 pixels from the top (the external monitor is 1280x1024, but the laptop display is 1280x768). So I placed it at the top of the display, added a taskbar applet to it, and voila I had what I wanted – but when I rebooted, the panel showed up on the laptop display again.

Otherwise I haven’t noticed any troubles. Anyone who has suggestions on these issues, feel free to post a comment!

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