Comment 12 for bug 246585

Further debugging on IRC reveals that gdk_screen_get_n_monitors() is returning 0:

$ python
>>> import gtk
>>> gtk.gdk.screen_get_default().get_n_monitors()
0

However, both xrandr and xinerama seem to return sane values:

$ xrandr --verbose
Screen 0: minimum 1680 x 1050, current 1680 x 1050, maximum 1680 x 1050
default connected (normal)
 Identifier: 0x63
 Timestamp: 3676687
 Subpixel: horizontal rgb
 Clones:
 CRTCs: 0
  1680x1050 (0x64) 0.0MHz
        h: width 1680 start 0 end 0 total 1680 skew 0 clock 0.0KHz
        v: height 1050 start 0 end 0 total 1050 clock 0.0Hz

$ xdpyinfo -ext XINERAMA
[...]
number of screens: 1
[...]
XINERAMA version 1.1 opcode: 150
  Xinerama is inactive.