Partial declarations of must not specify different base classes

I wanted to use a common base class for a set of UserControls in my WPF application, but when I changed the class’s ancestor in the code file and compiled I would get the error

“Partial declarations of must not specify different base classes”

This is because when you compile a WPF application Visual Studio generates a partial class in a code-behind file automatically, the base type specified is always “UserControl”.  To solve this problem change your XAML from this

 <UserControl
   x:Class="MyApp.MyControl"
 />

To this

<local:SomeBaseTypeYouWantToUse
  x:Class="MyApp.MyControl"
  xmlns:local="clr-namespace:NameSpace.To.Your.BaseClass"
/>