title: Applying function on a value returned from MarkupExtension in XAML
body: <p>Is there a way to apply a function on a value returned from a MarkupExtenstion such as</p>
  
  <p>{Binding ... } or {StaticResource ...} in XAML?</p>
  
  <p>Usage example: making the font size of button1 to be twice bigger than the font size of button2?</p>