There's another possible workaround usable by a set of programs sharing
one client library (e.g. GNOME, or KDE). When the owner of the clipboard
(or, I suppose, the selection) terminates, it sends the supported formats
to some persistent daemon whose job it is to take ownership in this
situation, and hand things on. If the size of all supported formats is
large, the application could request user confirmation and throw away the
clipboard/selection if the user requests.
This is not rocket science: Word for Windows 1.0 could do it back in the