Calendar drop freeze the app

Did nobody of you faced up with a calendar “freeze” while dropping an item in it ?
That can be easily reproduced with the CalendarDragAndDropDemo provided by Vaadin: just drag an event type just between two cells - whatever is the calendar view mode - and the event remains stucked. You cannot do anything else than reloading the app. I noticed that this occurs more frequently in the month view. On the code side, DropHandler.drop() is not called neither getAcceptCriterion();

Is this a known bug ? Do you have a patch for that ?
Please help.

Has been reproduced with the latest Calendar 1.0.1 version.

create a ticket
about this.

Done. The ticket number is #6921.