I just ran into a weird issue. During profiling I saw that controls on a form which was already closed were still reacting to events. I checked whether the Dispose() routine of the particular Form was called, but it wasn't. However, the Dispose() routine of other forms was called after it was closed, as in: immediately.
Have you ever ran into database tables with a field which is used to mark if a row has been 'deleted' ? Probably. These fields are used to implement 'soft-deletes'. For the soft-delete impaired, a quick introduction. Soft-deletes are row deletes which are not really happening: instead of removing the row from the database table, a field in the row is set to a value which signals that the row is officially 'deleted'. Every SELECT statement on that table is then filtering on that field's value so only rows which aren't marked as 'deleted' are returned (as the deleted data is not there anymore, semantically).