Also, if you are just noodling with no definite "time-frame" in mind, you can drag the "looping" part into the Matrix View, be sure it is set to "Follow Transport" and click "play" on that cell... it will blink till you hit play/record on the transport and then start, and loop until you stop it. While doing so, you can arm another track (
no loop area selected), and record it to your heart's content.
Caveat for this - you will want a marker (or start at a given time manually) using the above, as the loop start time is dependent on where the Now Time cursor is located when you hit play/record.
Good for noodling with no defined endpoint though.