who "cleans" windows on withdraw?

[Havoc Pennington <hp redhat com>]

Hi,

We have several properties that are taken as the initial state when a
window is first mapped, then kept updated with the current state by
the window manager.

e.g. _NET_WM_DESKTOP.

Some apps open a dialog, and when the user closes the dialog the app
just withdraws it, and next time the user opens that dialog the app
maps it again.

If no one does anything special then the dialog has _NET_WM_DESKTOP
set on the second map, which means that it will come up on its old
desktop, not on the current active desktop.

If the window manager clears _NET_WM_DESKTOP when unmanaging windows,
then restarting the WM or switching WMs has the unfortunate side
effect of dumping everything onto desktop 0.

If the toolkit has to clear _NET_WM_DESKTOP on window unmap then 
there are issues with legacy apps not doing so, probably.

_NET_WM_STATE has the same problem.

It seems to me that having the WM clean up windows when unmanaging
them is probably best, and perhaps for a clean WM restart a WM could
have a special mode where it didn't clean things.

But I'm wondering what other people are doing or expecting here.

Havoc