A thread is a few pieces joined by hand. Its name rests at the row’s edge, unseen until the pointer is near; point at it and the other pieces open beneath, the row above still in view.
A touch screen has no pointer to wait for, so the thread’s name is simply there under its row. Tap it and the list opens in place; tap a piece and you go to it, opening into it the way a piece always does.
Go back and you are on the very row you left, the list closed and the page exactly where it was. A thread joins pieces; it never loses your place.