I learned that i can create a customized lightbox using
scheduler.showLightbox
and
scheduler.startLightbox
But within in my customized lightbox i need to show the time slot period i have captured from dragging on scheduler. What i don’t know is how can i find out start time and end time of that dragged period? 
You can access event object in the custom lightbox functions
scheduler.showLightbox = function(id){
var ev = scheduler.getEvent(id);
var start_date = ev.start_date;
var end_date = ev.end_date;
...
}