Prevent Pasting Images Into RichTextBox In WPF

Xaml code
  1. <RichTextBox DataObject.Pasting="RichTextBox_Pasting" Width="770" VerticalScrollBarVisibility="Auto" .... />  
c# code
  1. private void RichTextBox_Pasting(object sender, DataObjectPastingEventArgs e) {  
  2.     if (e.FormatToApply == "Bitmap") {  
  3.         e.CancelCommand();  
  4.     }  
  5. }