GNOME versus projectors

My post about my new not-working-automatically Monitor reminded me of something that I forgot to follow up, though it’s probably unrelated.

At FOSDEM in February 2007, I muttered to X man Keith Packard that my laptop (with Intel graphics) didn’t work with the projector. I complain to everyone about this at all conferences, because it never works for me, regardless of laptop or projector model. Either the size is wrong or the sync rate is wrong or there’s nothing to give me any clue. It often works up to the login and then stops working after I’ve logged in. So I always borrow someone else’s laptop at the last moment. This is just one reason why my presentations are always shit.

But Keith dropped a clue. He said that immediately after login GNOME reset something that breaks things. I chased him about it in email afterwards and he said
“Oh, I found it — if your configuration settings include a monitor size, gnome would randr you to that size. I can’t remember where that was as I deleted it from my config though.”

Can anyone do something with this nugget of information?

7 thoughts on “GNOME versus projectors

  1. Hi Murray,
    If Keith is referring to your xorg.conf instead of some gnome preference, this will indeed be going away soon. We’re moving towards shipping with a minimal xorg.conf in Debian and Ubuntu will follow us when it’s stabilized a bit. This config won’t have monitor settings by default, letting the driver query the monitor at runtime for the information. You’ll be able to override it in xorg.conf if the monitor or driver gets it wrong of course.

    – David Nusinow

  2. David, he seemed to be referring to something that GNOME did if that setting was in xorg.conf, but I guess not ever having it in xorg.conf would fix it just as well.

  3. I believe if you set something in System/Preferences/Screen Resolution, then it can have trouble when switching monitors. The setting lives in /desktop/gnome/screen/${hostname}/0/resolution (if you saved it)

  4. It’s the display capplet in control-center (at least on my slightly old gnome). The gconf keys are /desktop/gnome/screen/$hostname/$screennum/.

    There are two much better interfaces that use newer Xrandr-1.2:

    http://dekorte.homeip.net/download/grandr-applet/
    http://xorg.freedesktop.org/archive/individual/app/grandr-0.1.tar.bz2

    grandr-applet was written by Matthew Allum of OpenedHand, and grandr was written by the Intel X guys (including Keith Packard).

  5. Murray, if you want to know exactly what GNOME does with xrandr at session startup, have a look at:

    http://svn.gnome.org/svn/gnome-control-center/trunk/gnome-settings-daemon/gnome-settings-xrandr.c

    This case has been moved from gnome-session to gnome-control-center very recently for GNOME 2.22. So, if you want to change this still in GNOME 2.20, have a look at:

    http://svn.gnome.org/svn/gnome-session/branches/gnome-2-20/gnome-session/gsm-xrandr.c

    I hope this helps!

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