In continuation to this (https://forums.daypilot.org/Topic.aspx/4356/how-to-remove-default-mousedown-event-on-calendar-events) question, check uploaded image.
I tried what you suggested but still the 'drag-start' event is not fired unless I remove 'mousedown' event from 'div.calendar_default_event'. [Tried by removing 'mousedown' event manually in inspect element window for div.calendar_default_event, dragstart was fired].
Div 'dndDroapableWorkshift' is inside the 'Event', which has another div inside it'Tile' which will be dragged. Hightlighted dragstart event is on 'Tile', which only gets fired when I remove 'mousedown' from highlighted div.calendar_default_event.
I tried adding mousedown to 'Tile' , it gets fired properly but after mousedown 'dragstart' is not fired.