how to get double empty click

how to get double empty click to make my own popup

scheduler don’t have such event, but you may try override scheduler.addEventNow. Scheduler calls this method to create new events on double click. The provided arguments are:
scheduler.addEventNow(start_date, null, browser_event);

i m using my own popup so when double clicking on an empty area that should open my popup so how can i override double clicking

You can override default lightbox by using

scheduler.showLightbox = function(id){ ...custom code... };

In such case your custom code will be called each time instead of default lightbox.