We found out while working on https://phabricator.mitk.org/D523#16388 that the MultiLabel plugin view reacts on a new empty segmentation that has been added to the data storage by another plugin (e.g. the segmentation plugin view). The auto selection mode leads to a call to QmitkSingleNodeSelectionWidget::OnNodeAddedToStorage which in turn triggers QmitkMultiLabelSegmentationView::OnSegmentationSelectionChanged. We noticed this because the call to QmitkMultiLabelSegmentationView::OnSegmentationSelectionChanged initializes the views which was undesired.

The general problem here is that the QT signal-slot connection to QmitkAbstractNodeSelectionWidget::CurrentSelectionChanged is still valid, even if the MultiLabel plugin view is hidden.
This might be a general problem for different selection-changes and will not only occur with the two mentioned plugin views.