Event for override-redirect change

[Devin J. Pohly]

The override-redirect flag is important for a window manager to know 
about, but there's no notification made when a window changes it.  It 
doesn't appear that the protocol specifies an action to take when a 
ChangeWindowAttributes request changes override-redirect.

It seems that the ConfigureNotify event might suit this, since it has an 
override-redirect field, and bears no meaning beyond "hey, recheck these 
values."  The other choices within the current protocol would be 
Create-, Map-, and ReparentNotify, all of which have a more specific 
meaning.

So... I propose that a ConfigureNotify event be generated when a 
ChangeWindowAttributes request changes override-redirect, and that this 
be sent to any client which would normally receive a ConfigureNotify.

How this would interact with ConfigureRequest events, I submit to the 
wisdom of the list.  I'd tentatively suggest that ConfigureRequests not 
be generated when override-redirect changes, since the ConfigureRequest 
event has no corresponding field, and the window manager shouldn't stop 
a window from setting the flag.  But I'm no X wizard - I'm just a guy 
hacking on a window manager. :)

Cheers!
*dp