There are LEAVE and ENTRY events that reference the browse object itself. For example:

On ENTRY OF OrderBrowse
  DO:
    .
    .
    .  
  END.

You can also write LEAVE and ENTRY triggers for individual columns. These triggers can refer to fields in the current row and can set and get attributes of the current cell by using either the name of the column in the browse or the SELF keyword. For example, you can enable the PO column in the OrderBrowse and then define this LEAVE trigger for it:

DO:
  IF Order.PO:SCREEN-VALUE IN BROWSE OrderBrowse BEGINS "X" then
    Order.PO:BGCOLOR IN BROWSE OrderBrowse = 12. /* RED */
END.

Or more simply, you can use the SELF keyword to refer to the cell:

DO:
  IF SELF:SCREEN-VALUE BEGINS "X" THEN
    SELF:BGCOLOR = 12. /* RED */
END.

Either way, you see the result shown in the following figure when you run the procedure.

Figure 1. Result of column event example