widgetDragController = new PickupDragController(this.boundaryPanel, false);
widgetDragController.setBehaviorMultipleSelection(false);
widgetDragController.addDragHandler(demoDragHandler);
int count = 0;
for (FlowPanelWithSpacer columnPanel : columns) {
FlowPanelDropController widgetDropController = new FlowPanelDropController(columnPanel);
widgetDragController.registerDropController(widgetDropController);
int random = Random.nextInt(2);
for (int i = 0; i <= random; i++) {
addTask("Task #" + ++count, columnPanel);