Mouse Clicks BR Button 1: Sets the cursor, drawing it in the new location, and marks the clicked vertex. BR Button 2: Sets the cursor without drawing it in the new location and unmarks the clicked vertex. BR Button 3: Clears marked vertices.
Mouse Controls for Zooming BR Control+Button 1: Zooms in, doubling the zoom level BR Control+Button 3: Zooms out, halving the zoom level