xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="WPF" Height="150" Width="300">
CommandTarget="{Binding ElementName=rtbTextBox}"
Content="Left" IsChecked="True"/>
CommandTarget="{Binding ElementName=rtbTextBox}"
Content="Center" />
CommandTarget="{Binding ElementName=rtbTextBox}"
Content="Right" />
Path=SelectedItem.Content}">
this is a test