reparenting widgets

[Carl Nygard <cjnygard fast net>]

I've got a widget sub-hierarchy rooted in a VBox that I want to reparent
into a floating window (and back again).  This VBox serves as the root
for a bunch of different panels that get swapped in and out.  They are
all created with glade files, actually one glade file for the main
window, and separate glade files for all the sub-panels that get swapped
in.

Originally, reparenting from the separate glade files into the main
window works fine (this is done via the GladeXML::reparent function). 
However, once I start reparenting the VBox into the floating window, the
individual panels start going all picasso on me, with widgets
repositioning themselves in wierd ways, usually with origin in top left
corner.

Reparenting from the floating window back to the main window fixes
things, even letting me reparent back to the floating window with no
picasso effects.  

However, switching panels (show/hide) while in the floating window then
causes some panels to picasso.

And there's no visible pattern, some work, some don't first time
through, but all bets are off for each Nth iteration.

Any clues?  The floating/main reparent operation is using the
Gtk::Window::reparent and not dealing with GladeXML::reparent function. 
Could that be a problem?

Any other clues?

Regards,
Carl