I'm using an UltraWinGrid v8.2

I'm setting the datasource of the grid equal to a generic list of objects (entities).  I've got the grid configured to be read only.  No values can be changed

One of the properties of each entity is of type DateTime.  This sets the corresponding column in the grid to behave like a UltraDateTimeEditor.

My problem is that when a cell located in the column described above receives focus, a button appears that when clicked a calendar appears for date selection. 

How do I make this button go away?