Как обратиться к элементу Label?
<Button x:Name="but" HorizontalAlignment="Left" Margin="256,126,0,0" VerticalAlignment="Top" Width="237" Height="183">
<Button.Template>
<ControlTemplate TargetType="Button">
<Grid>
<Label x:Name="txt" Height="100" Width="100"/>
</Grid>
</ControlTemplate>
</Button.Template>
</Button>