WPF：CellEditingTemplate如何通过双击或单击来设置内部控件的焦点

I wrote a usercontrol of DataGrid with CellEditingTemplate. The DataTemplate of this editing-Template is a TextBox, and the cursor will go into the textbox by three times click, what can i do, if i want set the cursor on the textbox by double click or one click?I wrote a usercontrol of DataGrid with CellEdit