Support for more XAML Resources (Brushes)

Would be great if the designer support LinearGradient, RadialGradient and Image brushes. Using images seems so clunky when it would be relative simple. I even tried adding like:

  <LinearGradientBrush x:Key="DefaultColorMapBrush">
    <GradientStop Offset="0" Color="DarkBlue" />
    <GradientStop Offset="0.5" Color="CornflowerBlue" />
    <GradientStop Offset="1" Color="#FF22AA" />

In the exported Resources.xaml but that does not work, it is just lost on reimport.