On Wed, 13 Jun 2007 00:33:10 +1000 Aldo Cortesi wrote:

Hi folks,

I'm seeing symptoms similar to the the same Xinerama-related problem reported here:

http://www.haskell.org/pipermail/xmonad/2007-June/000491.html

In that same thread, Jason Creighton suggested running the following test script:

""" import Graphics.X11.Xlib import Graphics.X11.Xinerama

main = do d <- openDisplay "" xineramaQueryScreens d >>= print getScreenInfo d >>= print """

On my system, this outputs:

""" Nothing [Rectangle {rect_x = 0, rect_y = 0, rect_width = 1920, rect_height = 1200}] """

Now the plot thickens. The following snippet of C should be very nearly equivalent to the script above:

""" #include #include #include #include #include

int main (){ Display *dpy; XineramaScreenInfo *xsi; int i, num; dpy = XOpenDisplay("\0"); printf("%s\n", XDisplayString(dpy)); if((xsi = XineramaQueryScreens(dpy, &num))) { printf("%i screens\n", num); for(i = 0; i < num; i++) { printf("%i: %ix%i\n", xsi[i].screen_number, xsi[i].width, xsi[i].height); } XFree(xsi); } XCloseDisplay(dpy); return 0; } """

However, from this, I get the following output:

2 screens 0: 1920x1200 1: 1280x1024

As you can see, the Xinerama screens are detected correctly. Xinerama under other window managers (e.g. KDE) also seems to work flawlessly with the same X configuration. Despite this is being my first real foray into Haskell, I bravely ploughed through the appropriate bindings in X11-extras and X11-1.2.2, but I could see no obvious errors.

I have a hunch that the problem is related to the fact that I have an NVidia graphics card with TwinView (NVidia's magic sauce that allows you to connect multiple screens to the same GPU). Apparently, Twinview is known to cause problems with some window managers - see, for example, the FAQ section of this page from NVidia:

http://http.download.nvidia.com/XFree86/Linux-x86/1.0-8178/README/appendix-g...

The FAQ entry is pretty vague about exactly what form these "problems" might take.

I'm keen to give XMonad a try, so I'd be happy to spend time helping to troubleshoot this problem...

Cheers,

Aldo

Are you running X11-extras from darcs? If so, did you run 'autoreconf' before running 'Setup configure'? (this step isn't required if you're compiling from a release tarball) Watch X11-extras configure output for: checking X11/extensions/Xinerama.h usability... yes checking X11/extensions/Xinerama.h presence... yes checking for X11/extensions/Xinerama.h... yes Hope that helps, Spencer Janssen