The OnClientTabDragStart event is fired when a drag-to-reorder operation is about to start.
This event will be fired only when the EnableDragToReorder property is set to "true"
The event handler function receives two parameters:
The instance of the tabstrip firing the event.
An eventArgs parameter containing the following methods:
get_tab returns a reference to the RadTab which is about to be dragged.
get_domEvent returns a reference to the DOM event object for the action that caused the drag-to-reorder operation to start.
set_cancel lets you stop the operation by passing boolen value as a parameter.