title: TextBox Cursor is NOT blinking
body: <p>I have a WPF datagrid (4.0) with a custom column (derived from DataGridTextColumn).</p>
  
  <p>In GenerateEditingElement I create a custom textbox control (with an additional button) and like to set the cursor into it so that the user can directly start editing.</p>
  
  <p>The closest I get is that the caret is shown but is not blinking and I need an additional click to start editing.</p>
  
  <p>All other stuff (binding, ...) is working nicely</p>
  
  <p>Any ideas?</p>