List box when displayed event

You can add a RowTag for the row you’re currently performing an action on, something like

myList.AddRow( "Cell 1", "Cell 2", "Cell 2" )
myList.RowTagAt( myList.LastAddedRowIndex ) = True

Then, in myList’s PaintCellBackground event:

If row < 0 or row > me.LastRowIndex then Return

If me.RowTagAt( row ) = True Then
  g.DrawingColor = &cFF00FF
  g.FillRectangle( 0, 0, g.Width, g.Height )
  Return True
End If

And, finally, at the end of your process that loads your data, you can set that row’s tag to False to display the default colors.