Yeah, rolling your own is probably a bad idea in most cases. My implementation doesn't generalize at all really and I only need to support desktop browsers. If

Yeah, rolling your own is probably a bad idea in most cases. My implementation doesn't generalize at all really and I only need to support desktop browsers. If I ever own source this app I'll let you know. But basically I have one component listening to mouse events and firing callbacks with the rectangle the user has dragged (mouse down point to most recent mouse point), and with that my state manager updates things accordingly and drops upon mouse release.