In earlier versions of Caddie Option End on the context sensitive menu could be used to unselect objects.
The selection is vastly more flexible in Caddie 16, with the ability to select by polygon, rectangle, crossing, outside polygon, outside rectangle, etc etc.
Some of these functions require an Option End (similar to mark), therefore Option End cannot unselect objects in Caddie 16.
The context sensitive menu now has an abort option (which has the same functionality as the escape key on the keyboard). Use this function to terminate commands rather than Option End.