Inspiration from John Gossman, and access to AvPad's sources... as soon as the new CTP is released this code will run inside of AvPad... oh yeah, that's what i'm talking about!

<?Mapping ClrNamespace="System" Assembly="mscorlib" XmlNamespace="Sys" ?>
<?Mapping ClrNamespace="AvPad.Controls" Assembly="AvPad" XmlNamespace="application/avpad" ?>
<Grid
    xmlns:sys="Sys" xmlns="http://schemas.microsoft.com/winfx/avalon/2005"
    xmlns:x="http://schemas.microsoft.com/winfx/xaml/2005"
    xmlns:ap="application/avpad"
  >
  <Grid.Resources>
  </Grid.Resources>
  <Button Name="_button" HorizontalAlignment="Center" VerticalAlignment="Center">
      Hello World
  </Button>
<ap:PyScript xml:space="preserve">

def click(sender, e):
  MessageBox.Show('hello')

_button.Click += click
</ap:PyScript>

</Grid>