Is it possible in Silverlight 4 to create a border with rounded corners that clips any of it child UI Element? So far I have attempted to do so by setting a button as a child element of a border control but the buttons does not get clipped when I set the corner radius to create rounded corners in the border.
Take a look at the ClippingBehavior that is part of the Expression Blend Samples on CodePlex. It's a Blend behavior, so to add it you have to reference System.Windows.Interactivity.dll from the Blend SDK and drop the behavior on the element in Blend or add it in XAML:
<UserControl x:Class="MyApplication.MainPage"
...other xmlns imports...
xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"
xmlns:samples="clr-namespace:Expression.Samples.Interactivity;assembly=Expression.Samples.Interactivity"
>
<Border>
<i:Interaction.Behaviors>
<samples:ClippingBehavior CornerRadius="15"/>
</i:Interaction.Behaviors>
<!-- content to be clipped goes here -->
</Border>
</UserControl>
This is a straightforward and reusable way to add rounded corners/clipping to any UI Element.