Bill,

In the context you describe no public event is raised/exposed for
handling.  You may be able to handle the windows messaging event
directly by overriding WndProc() and handling the appropriate message
but I think you should examine and rethink your current approach
before attempting to go this route.  My suggestion requires a lot of
work for something that might be solved more effectively in a
different layout or using different controls (tablelayout,
flowlayoutpanels, splitters, etc).

Without knowing anything about your requirements or why you have
implemented your layout in this manner, one suggestion I will make is
that you might want consider nesting the panel the labels are in into
the panel containing the text boxes.  This is assuming of course that
there is at least one valid reason why they absolutely must be in a
seperate panel in the first place.

Good luck,
-- Geoff