TreeGrid cell background image

I need to let users know that a combobox excelltype must be double-clicked to dropdown the options.



Is it possible to set a background image for a cell that is a combobox or can you suggest another way to clearly show users that a cell is a combobox and must be double-clicked?



thank you.

There is no way to defined custom style per column, but you can do it for necessary cells directly from XML
   
       Some here
       Some here
       Some here