This short bit from Ableton's Learn Live series covers the modifier-key pattern for showing and hiding panels in Live's interface. On Mac, Cmd+Option paired with a letter controls each panel; on PC, the same logic applies with Ctrl+Alt.
The six shortcuts covered: L toggles the Detail View, S toggles Sends, R toggles Return tracks, M toggles the mixer, I toggles inputs/outputs and routing, and B toggles the browser. The same key press both hides and reveals each panel, so there's nothing extra to memorize.