I can't find a way to Lower a window in the Gnome desktop manager
on Linux (I also used to call it 'push to back').

For example, since the beginning its been possible to assign
key sequences + mouse clicks to window operations like Raise,
Resize, Move and Lower.

It seems Lower is now missing in Gnome. I think its important- its a big 
problem in all versions of MS Windows that you can't lower and from a 
usability perspective it sets Unix systems in front of Microsoft's  
systems. I usually bind lower to something like Alt + LeftMouse and
it really lets you blitz through the windows on the desktop- very helpful.

I'd be willing to write it with just the least of help.

Thanks.