As one who is cuurently at the end of a game design class, not as far as I know. I have for you a tip, however. the blue line you see when you drag and drop events tells you where the event ends up, as you probably know. BUT, the size of the blue line tells a LOT. when you're dragging an event, the blue line being shorter means you're going to make the dragged event a SUB-EVENT to the event that the blue line is under. use precision to make the blue line larger when dragging events to make it an event just underneath the event over the blue line. to unsub events, you can drag the sub event to the left until the helpful blue line reaches the left end of the non-subbed event.
Hope this helps! :)