context.py = Dygraph.findPosY(g.canvas_);
context.dragStartX = g.dragGetX_(event, context);
context.dragStartY = g.dragGetY_(event, context);
context.py = Dygraph.findPosY(g.canvas_);
context.dragStartX = g.dragGetX_(event, context);
context.dragStartY = g.dragGetY_(event, context);