Crash bug 170693 seems to have been fixed by checking whether the window given WindowWatcher as the new active window is a genuine, top-level window. This implies that nsFocusController sometimes attempts to set the active window before the window's docshell hierarchy has been built up all the way to the root. (See bug 170693 comment 23). With the crash fix checked in (it is), we know that WindowWatcher's active window reference is now sometimes incorrect. This is not a fatal problem, but it could leak to irksome issues finding the correct parent for dependent windows. Perhaps there are other side effects as well. Hard to say, since no one with a debugging build has ever been able to reproduce this problem. To make the focus-or-activation situation well, nsFocusController wants at least to note when window activation fails (wwatch->SetActiveWindow in nsFocusController::UpdateWWActiveWindow() will return an error code), and schedule another attempt to set the active window later, once the entire docshell hierarchy has loaded.
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