..., and a fix to avoid Gorm crashes

[Wolfgang Lux]

Gorm crashes more or less reliably when opening and closing multiple
documents. These crashes are due to dangling document pointers which
are not removed from the (private) document maps maintained by various
editors. Actually, GormImageEditor and GormObjectEditor contain code
to remove those pointers from their respective maps, but this code has
been commented out (apparently as a temporary "fix" to avoid crashes
because the respective code is sometimes invoked too late, i.e., after
the document has been released). Since the editors cannot retain the
documents without introducing a reference cycle, the correct solution
is to observe the IBWillCloseDocumentNotification notifications posted
by the document. This is implemented by the attached patch.

Wolfgang

gorm-fix.patch
Description: Binary data