Hi Matthieu,

Do you confirm that you set the volume type for the mask to be "LabelMap" ?

More details available on the wiki: http://www.slicer.org/slicerWiki/index.php/Documentation/Nightly/Extensions/SwissSkullStripper

Thanks for reporting the issue. There is a clearly a usability problem.

Otherwise, changing the type to labelMap, i was able to select the mask.

If you load the mask as a labelMap [1] or go into the volume module to change the type to label map, it works as expected.

[1] http://wiki.slicer.org/slicerWiki/index.php/Documentation/Nightly/SlicerApplication/LoadingData#Show_Options

[2] http://wiki.slicer.org/slicerWiki/index.php/Documentation/Nightly/Modules/Volumes#Panels_and_their_use