title: Set focus on AutoCompleteBox in DataGridTemplateColumn
body: <p>I have an AutoCompleteBox inside the CellEditingTemplate for a DataGridTemplateColumn and I am trying to auto-focus on it after a certain number of characters have been entered in a previous column.</p>
  
  <p>I have been able to get the focus to shift and the caret to set appropriately using the BeginInvoke method (described <a href="http://silverlight.net/forums/t/28726.aspx" rel="nofollow noreferrer">here</a>) but only if the control is a TextBox. when using this method with an AutoCompleteBox the caret does not set nor does the control appear to gain focus.</p>
  
  <p>I attempted to set focus on the AutoCompleteBox manually by obtaining a reference to it inside the setCaretInCurrentCell method and invoking focus but that didn't work either.</p>
  
  <p>I really wannt AutoCompleteBox functionality in this column but the datagrid needs to be optimized for data entry which meeans if the users can't tab or automatically be taken to the next field its a show stopper.</p>
  
  <p>Thanks.</p>