@Override public void addWidget( WidgetToShow widget, boolean removable, @Nullable WidgetRemovingListener widgetRemovingListener) { // just activate the widget if it's already exists on the panel if (widgets.contains(widget)) { activateWidget(widget); return; } widgets.add(widget); if (widgetRemovingListener != null) { removingListeners.put(widget.getWidget(), widgetRemovingListener); } view.addWidget(widget, removable); }