The situation: A window is created, say `.w1`, followed by another
window, say `.w2`.  The command `pack .w1 -in .w2` is used to pack `.w1`
inside of `.w2`.  The `pack` command completes successfully, and `pack
info .w1` indicates that things are as expected.  However, `.w1` isn`t
visible!  Where is it?

	button .w1 -text Hello;	# create .w1
	frame .w2;		# create .w2
	pack .w1 -in .w2;	# pack .w1 inside .w2 
	pack .w2;		# pack .w1 in main window
				# where`s the button?

The explanation: (based on a posting by js@aelfric.bu.edu (Jay Sekora))

The short answer is `raise .w1`.  In the example `.w1` is positioned
properly inside `.w2`, and all the sizing glue that lets `.w1` and `.w2`
adjust their sizes based on each other will work, but `.w1` is
underneath `.w2`, because windows are stacked in the order they are
created in, by default.  You can change the stacking order explicitly
with the `raise` command, in this case `raise .w1`.