If you include the namespace of your base class UserControl, you can do this as long as you use the namespace. For example:
public abstract class MyBaseUserControl : UserControl
{
}
XAML ( , ):
<my:BaseUserControl
x:Class="SilverlightApplication11.Page"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:my="clr-namespace:SilverlightApplication11"
Width="400" Height="300">
<Grid x:Name="LayoutRoot" Background="White">
</Grid>
</my:BaseUserControl>
, :
public partial class Page : BaseUserControl
{
public Page()
{
InitializeComponent();
}
}