So, I’m looking for the colored threads feature. No mention of “thread” in the manual, which seems to be the feature term on the site.
In Corkboard, select “Sort by Label” and it comes up. It’s called “Label View.” GTK, but the feature list is a bit confusing
Tracks, threads, rails… we went through a few different terms for what to call them and I might have missed where the string ended up. 
I’ll make sure the manual has a few extra terms thrown in that section for spice in the next revision.
Page 169, §8.2.5 by the way!