The opportunity to unfold/fold variations in the pgn window:
1.d4 d5 2.c4 c6 [+] 3.Nf3 Nf6 *
1.d4 d5 2.c4 c6 [-] ( 2...e6 3.Nc3 c6 ) 3.Nf3 Nf6 *
Clicking on [+] unfolds the variation, [-] folds the variation.
via popup menu it is possible to fold/unfold all variations at once
possible implementation see https://github.com/benini/scid/pull/200