1. Client-side selection.
It's not yet possible to select an event using JavaScript when you know the DayPilotCalendar.Event object. It will require a few tweaks in the source code. I will add it in the next release (
DayPilot Pro 3.9, August 1).
2. Double-clicking an event.
I will give it a thought. That would collide with the standard click event. One of the possible ways is to handle the click using JavaScript (you get the DayPilotCalendar.Event object), set a flag property for double click, set a timer that will reset the flag after a given time. If the click event happens again when the flag is still set, you know you got a double-click. It's a little bit of a hack and I haven't tried it.
But I will consider double-click event for the next release (DayPilot Pro 4.0). If you want to get a beta of this feature when it's done, please contact me at daypilot @ annpoint.com.