If the master for a slave is not its parent then you must make sure
that the slave is higher in the stacking order than the master.
Otherwise the master will obscure the slave and it will appear as
if the slave hasn't been packed correctly.
The easiest way to make sure the slave is higher than the master is
to create the master window first: the most recently created window
will be highest in the stacking order.
Or, you can use the raise and lower commands to change
the stacking order of either the master or the slave.