MVC design question

["Paul Davis" <pjdavis engineering uiowa edu>]

List,

I've never been able to keep a good MVC design split with gtkmm (or
any gui toolkit for that matter).

My basic concern is having multiple copies of some values that are
displayed in a gui. For instance, imagine we have a double value
stored in some user object.  This value gets mapped onto an HScale in
the GUI.  There are effectively two copies of this value (one in the
user object, one in the hscale) that need to be kept in sync.

I'm mostly interested in what other people have done to get around
this and similar types of problems from a design stand point.

The only promising answer I can come up with is to create my core app
logic with some sort of its own call back system, then have a GUI
toolkit specific layer that sits between my custom app code and the
toolkit of choice.

Anyway, if anyone has any pointers, I'd be glad to hear them.

Paul Davis