Thx for the solution.
It’s an older blog post so I didn’t check if the problems still exists in Blend 3

This solution take in account that your base class is in another project ( let say your Framework ), but of course work also if in the same project, with the same processus ( it’s just to show that it is possible too ).

Home.Xaml :

For adding the possibility of using the base class, add a “xmlns” to the property of your UserControl, Intellisense will give you automatically all the namespace you have in your project and dll, just choose the one where your HomeBase is, and you’ll have something like :

xmlns=”clr-namespace:Framework;assembly=Framework”

Then add it a name to use it in the Xaml File :

xmlns:Base=”clr-namespace:Framework;assembly=Framework”

Finally change your to something like where HomeBase is your base class and Base the name you gave to your xmlns reference.

Here is what you should have =>

Home.Xaml.cs :

namespace SilverlightApplication
{
public partial class Home : HomeBase
{

…

}

}

And it’s done

Rmk : If you use Expression Blend 3, be aware that using abstract class as Base will make Blend unable to display your Xaml file ( even if all works fine .. ), and you need to create a default Constructor without parameter too or again, Blend won’t display your xaml file.

Thanks for a Nice Write UP !!!