This is Insider TA's Point & Figure Zoom button. It is accessible only if you enabled Point & Figure charting by clicking the Point & Figure button.
Click the zoom button to pop up a secondary window that displays a magnified region of your Point & Figure graph, for which you will now see a blue rectangle. Grab any side or corner of this blue rectangle with the mouse, and drag it around the Point & Figure chart. You will see the contents of the the zoom window shift accordingly.