Description of problem:

The GNOME window list applet, which I assume is wnck-applet, doesn't
work properly with Xinerama displays.

I have a dual-head system.  Whichever Xinerama screen the GNOME panel
 is displaying on, wnck-applet fails to display any windows from the
other Xinerama screen.

If I move the GNOME panel from one screen to the other, the list of
windows showing up in wnck-applet's list changes so that only the
windows on the new screen appear.

The criterion for whether a window is "on" a particular screen seems
to be whether the midpoint of the window is on that screen or not.

Version-Release number of selected component (if applicable):

gnome-panel-2.8.1-3

How reproducible:

100%

Steps to Reproduce:
1. Set up a multihead system.
2. Run GNOME.  Create windows on each screen.
3. Look at wnck-applet.  Notice that only windows on one screen
populate the window list.
  
Expected results:

I'd expect all windows to show up.