Comment 25 for bug 178953

Here are my thoughts.

Part one, the background reading: It seems to me after a while of digging through the ICCCM that Travis Watkins was incorrect back in December when he said that Metacity was not giving up control of the compositor selection. Section 2.8 of the ICCCM says that anyone who wants a selection can take it. The old owner is told they're losing it, but they don't get a choice in the matter. Obviously it was unhelpful when Metacity crashed at that point, but it no longer does. (Backport to stable is coming soon.)

Part two, the experimentation: I have experimented with the return results around the lines which Travis pointed out. Compiz, as you see, does not check the return result of XSetSelectionOwner. I have checked the result, and it is BadRequest. (In case of strange synchronisation oddities, I have performed the same experiment with an XSync on the previous line, with identical results.) BadRequest is a low-level problem in X itself or in Xlib; I don't know what might be going on here but it would appear to be at least as much a Compiz problem as a Metacity problem, since this error should never appear. I have therefore reopened this bug against Compiz.