>Thanks George,
>
>However I have tried setting the combo box's read only property to .f. in it's gotfocus method but somehow the control is set back to readonly at run time!
>
>I have been unable to find any docoumentation to explain this behaviour.
>
>Still Looking...

Steve,

Actually, I recalled incorrectly about my check box. Here's the actual code in the AddCheckBox method. This method is called when the RecordSource_Assign method is fired.

LPARAMETER tcField, tni

LOCAL locol as Column 
IF VARTYPE(&tcField) = "L"
  locol = EVALUATE("This.Column" + TRANSFORM(tni))
  WITH locol
    .RemoveObject("Text1")
    .AddObject("GridCk1", "GridCk")
    .Gridck1.Visible = .T. && This fixed the problem
    .Sparse = .F.
  ENDWITH
ENDIF
RETURN

As you can see by my comment, even though the check box was visible in the grid, not explicitly setting it ot .T. caused the check box to be read-only,