Please describe the problem:
In a previous version of metacity (not sure which one it was), click-and-hold on
the title bar of a full-screen window followed by dragging to the top of another
screen would move the window between screens.  It doesn't in 2.14; instead, the
window vibrates and resizes rapidly but stays on its own screen.

Steps to reproduce:
1. Go to a system with at least 2 monitors, with Xinerama.
2. Create a full-screen window.
3. Click and hold the title bar of the window, and drag to the top of another
screen.


Actual results:
The window vibrates and resizes rapidly.

Expected results:
The window becomes full-screen on the other screen.

Does this happen every time?
It does not always vibrate and resize, but it never moves to the other screen.

Other information:
This bug is easily worked around by other dragging behavior in Metacity: first
drag down, causing the window to lose full-screen status, then drag to the other
screen, then drag to the top, restoring full-screen status.