VLEXAMPLE - BASIC 5

                vlex="points:50,{$cY},{max(300,$cX-100)},{$cY-100},{$cX},{$cY},{max(300,$cX-100)},{$cY+100}"

                - the gray polygone should be centered vertically at stage
                - point 1 should be 50px from stage´s left edge
                - point 3 should be at stage´s center
                - point 2 and 4 should be 100px above/below and left from stage´s center
                - point 2 and 4 should be at least 300px from stage´s left edge