> IMHO the right fix is to throw an error for
 >
 >   if (NILP (w->buffer) && NILP (w->hchild) && NILP (w->vchild))
 >
 > which means that some functions when called on dead windows (like
 > `delete-window') will now throw an error.  These will have to be caught
 > on the Elisp level.

I think `delete-window-internal' can keep its decode_any_window.  I'm
not sure about `window-buffer'.  For the remainder, the attached patch
should be applied IMO.  Eli can you check whether this interferes with
tooltip creation?

martin