Put a NODEFAULT in the keypress event to stop the key press from being processed. Try this:

IF nKeyCode=13
  * Do whatever you want to do
  NODEFAULT
ENDIF

>Is there a way to avoid that focus changes from the active cell when pressing Enter in a grid?
>
>I have a two-column grid and I want to be able to select the current row when pressing Enter in the grid. I'm trapping the Enter in the Keypress method of the Text control in the first column, which works fine except for that focus also changes to the next column in the grid.