How to use masking in Segment editor


I have been working with the Segment Editor and Segmentation with good
success. I am very new to 3D Slicer and wondered if there was a tutorial
that would show how the segments (circles) were drawn in Slide 19. I have
been using the threshold effect, but cannot figure out how to use the “use
for masking/paint” feature which I think draws the regions shown in the
slide(?). Any pointers to documentation or videos would be greatly


See documentation of Segment editor. Search for Masking.