Handle() and Mousetrap() are functions for making interactive graphs that respond to clicking and dragging. Handle() lets you parametrize a graph by adding a handle-marker that can be dragged around with the mouse, executing the graph’s script at each new location. Mousetrap() is similar, but it takes its arguments from the coordinates of a click without dragging a handle. The main difference is that Handle() only catches mousedowns at the handle-marker’s location, but Mousetrap() catches mousedowns at any location.
Another approach is to place buttons or slider controls outside the graph with Button Box(), Slider Box(), or Global Box().