Parameters:
* context.start - ID of an item, from which drag process was started
* context.source - array of dragged IDs (drag source) * context.target - ID of target item (drop target) * context.from - view object, to which dragged item belongs * context.to - view object, to which drop target belongs * context.index - index in the target view, at which new item will be added * native event object.
view.attachEvent("onBeforeDragIn", function (context, ev){ //any custom logic here return true; });
Event is blockable, if non-true value returned from custom method, default reaction will be blocked