<UserControl .....>
 <Grid x:Name="GridGlobal">
 <DockPanel Background="White" Margin="5" >
        <StackPanel DockPanel.Dock="Left" HorizontalAlignment="Left"
Orientation="Horizontal" Margin="10 0 10 0">
            <StackPanel Orientation="Horizontal">
                <TextBox x:Name="txtCommandeUrl"  Width="500"
                   Height="24" VerticalAlignment="Center"  />
                <mui:ModernButton x:Name="btnSave" Content="{x:Static
                   p:Resources.Link_Save_Link}" Click="BtnSave_Click"
                   VerticalAlignment="Center" Command="{Binding
                  NextCommand, Mode=TwoWay}" IsEnabled="{Binding
                NextEnabled}"/>
            </StackPanel>
        </StackPanel>
  </Grid>
</UserControl>