When segmenting in MxN, the label nodes are currently not always visible, especially when using a data-based layout. Creating a new segmentation, by default, makes the node be listed below the image itself in the window-specific data selection, so the image is in the foreground. If the segmentation was already created before setting a data-based layout, the segmentation is not even selected for any window, since each window only shows its image and nothing else.

It might be useful to add an option to the data-based layout to include segmentation nodes that belong to the selected image.