If you are interested in my last post about "How to center and scale Silverlight applications using ViewBox control", I just published behavior that you can use instead of making changes in code.
How it works?
1. Download behavior (http://gallery.expression.microsoft.com/en-us/CenterAndScale )
2. Add dll to your application
<UserControl .....
xmlns:interaction="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"
xmlns:behavior="clr-namespace:CenterAncScaleBehavior;assembly=CenterAncScaleBehavior" .... >
<interaction:Interaction.Behaviors>
<behavior:CenterAncScaleBehavior />
</interaction:Interaction.Behaviors>
<Grid > ... </Grid>
</UserControl>
3. DONE! Your application is ready!
Watch movie to see how it works (66 seconds):
See examples
Application without "Center And Scale Behavior": http://bit.ly/cVinEC
Application with "Center And Scale Behavior": http://bit.ly/ba8UsI
Source code and dlls
http://gallery.expression.microsoft.com/en-us/CenterAndScale
Cheers!
Jacek Ciereszko