Keyboard/mouse control of Z-order?

[Chris Angelico]

Hi! Just this week switched to Xfce (my fingers keep wanting to type
XKCD) from GNOME, and finding it pretty comfortable. In fact, Xfce is
so close to what I'm looking for that I make bold enough to inquire
about some of my favorite OS/2 features.

Is it possible to set up a key/mouse command that moves a window in
the Z order? With our OS/2 boxes, we have it configured so that
Ctrl-Alt-RightButton will move the window under the mouse backward one
slot (and Ctrl-Alt-LeftButton moves the mouse one window upward,
toward the top). I've poked around in the settings and on Google
without finding a way to do this, but that doesn't prove it's not
there.

I'm a programmer, so if this requires a bit of code to implement, I'm
not afraid to do it. It's perhaps a niche feature, but once you get
accustomed to it, it's extremely handy.

Platform: Debian Wheezy amd64
Xfce version 4.8

Chris Angelico