Window History Placement

[Benjamin Kahn <xkahn ximian com>]

I'm writing a patch for Metacity which adds window history as a
placement method.  

You can find a description of my patch at:
http://bugzilla.gnome.org/showattachment.cgi?attach_id=13455

You can find a discussion of the patch at:
http://bugzilla.gnome.org/show_bug.cgi?id=91481
http://bugzilla.gnome.org/show_bug.cgi?id=81802

and the patch itself at:
http://bugzilla.gnome.org/showattachment.cgi?attach_id=13452

The biggest problem I had when saving window state is trying to find a
unique way to identify a window.  I eventually came up with an internal
numbering system.  Windows are identified by class/name/role/number
where number is simply an integer which grows as similar windows are
placed on the same virtual desktop.  This seems to work very well.

However, I needed a way for applications to control window history a
little better.  Some applications want to remember their own window
state and other applications want to make sure the window manager treats
a certain window the same each time and do not want windows to be
numbered.

Havoc suggested a window property called: _NET_WM_GEOMETRY_SAVE_ID.  If
this property is set with a string, my patch uses that as the history
identifier.  If the property is set with an empty string, my patch does
not save any state for the window at all.

It seems like this would make a nice addition to the window manager
specification.