OP VECTOR-X PROTOCOLS
1. CREATE: DBL-CLICK on empty space to start.
2. EDIT: DRAG any corner to reshape. DBL-CLICK an edge to add a corner.
3. MOVE: DRAG polygon centers. Shared corners stay "Glued".
4. VALUES: DRAG any measurement value to move its position.
5. REMOVE: CTRL + CLICK a corner to delete it. Press DEL to delete active polygon.
6. UNDO: Press CTRL + Z to revert last action.