How to move a window between monitors with Gnome Shell? [duplicate]

I see this question is "answered" by stating that there is no way to do this in GNOME: How to move windows around and between monitors, using keyboard short cuts? I have doubts that it should be impossible and I really want to do it.

Is there really no way to do this is Gnome? This is my output from xrandr that I don't know how to use:

$ xrandr
xrandr: Failed to get size of gamma for output default
Screen 0: minimum 3840 x 1200, current 3840 x 1200, maximum 3840 x 1200
default connected 3840x1200+0+0 0mm x 0mm
   3840x1200      50.0* 

Solution 1:

The following works for me (Ubuntu 12.10, Gnome Shell):

Ctrl + Alt + NUMPAD 6 moves the active window to the screen on the right

Ctrl + Alt + NUMPAD 4 moves the active window to the screen on the left

Note that, for some applications like Firefox and Thunderbird, this does not work for maximized windows for me -- the window seems to be moving, but only until I release the keys. This could be a bug in the corresponding applications or Gnome Shell. As a workaround, I unmaximize first using Ctrl + Alt + NUMPAD 5, and maximize back later with the same combination.

This is inspired by answers from How to move windows around and between monitors, using keyboard short cuts?.

EDIT: For some obscure reason these shortcuts stopped working for me. Super + NUMPAD 7 and Super + NUMPAD 9 achieve a similar effect.