<Window x:Class="Controls.ButtonWithShape"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="ButtonWithShape" Height="150" Width="258.8"
    >
   <Button Margin="10">
    <Grid>      
        <Polygon Points="100,25 125,0 200,25 125,50"
             Fill="LightSteelBlue" />
        <Polygon Points="100,25 75,0 0,25 75,50"
             Fill="White"/>      
    </Grid>
  </Button>
</Window>
