Comment 2 for bug 299549

This should be fixed by this commit, with prevents there ever being no primary key:

2008-11-25 Murray Cumming <email address hidden>

 * glom/libglom/utils.[h|cc]:
 Added a show_ok_dialog() overload that takes the parent_window as a
 pointer to simplify code by avoiding the need for a null check by
 callers.

 * glom/mode_design/fields/box_db_table_definition.cc:
 check_field_change(): Refuse to leave no primary key set because
 the rest of Glom expects each table to have one, by refusing to
 directly unset a primary key.
 When setting a primary key, ask the user if they really want to _change_
 the primary key, and do the suitability checks that were previously in
 change_definition().
 change_definition(): When setting a primary key, unset the previous
 primary key first.

 This prevents the table from ever having no primary key.
 Ubuntu bug https://bugs.launchpad.net/ubuntu/+source/glom/+bug/299549
 (elmergato)
 Glom bug #562147