- move vertexVertices are draggable.
- create vertexClick on empty space not too close to existing vertices.
- select a vertexClick on existing vertex.
- create/erase edgeSelect the first vertex. Click on another vertex (different than the selected one) to turn on/off (toggle) the edge between them.
- keep the selected vertexHold 'SHIFT' to perserve the selected vertex after creating/erasing an edge.
- delete vertexDouble click on vertex or drag to the edge for the frame (be careful, there is no UNDO yet!).