iCal is a somewhat-unique calendaring application. Unlike most of its competition, there are no borders around days or weeks in those respective views. Most other apps leave a border, which makes it easier to create overlapping events—just drag from the border area into an existing event’s block, and you’ll create a new overlapped event. So how do you do this in iCal if there aren’t any borders?
There are three methods, two of which may be obvious, while the third is anything but—and is the simplest solution. First, you could create a new event anywhere you want, and use the Info pane to change the date and time to overlap the existing window. Second, you could just use drag and drop to move a newly-created event from some other time slot into an overlapping position with the existing event.
While both of these methods work just fine, here’s the quick and easy way to create the overlapping event exactly where you want it in the first place. Press and hold Option and Command, and then just start dragging at the time you wish the new event to start—right on top of the existing event! For instance, if you have an existing 10:00am-11:00am meeting, and someone schedules a new one at 10:30am, just press and hold Command and Option, then line the mouse up at 10:30am on the existing event, and start dragging. iCal will drag out a new event as you move the mouse down, and then show the two events side-by-side when you’re done.
You may not have to create overlapping events every day, but when you do, just remember the Command-Option-drag trick to save yourself a bit of time.