If you create a Dialog object and call pack() on it, the dialog will become
mapped prematurely (even if show() is never called!). This causes the
Dialog to be visible even though it's state in "not showing" , therefore if
you subsequently call hide(), the Dialog will remain because it believes
it is not showing and doesn't need to be taken down.

I suspect that this may be a Solaris-only bug caused by a Motif idiosyncrasy.