this is a completely different patch :)

here's a new approach: have a sessioninteract var, and when it's set, *pretend* to be on all activities and desktops.

it shows the "do you want to save..." window nicely. however, it doesn't show the parent window containing the document. should it? (I think I can hack that in by setting the var on the parent too)

I preserved the 'allow' behaviour here, too, since I don't quite grok it.