Sometimes I'm listening and want to go back and listen to something that just passed. You can do it with mouse our touch.
 
For Touch, tap the ruler, then double tap again just below. For mouse, double click the ruler.
 
That works with no FX, but for some reason, with lots of FX on the mix, it isn't working for me. The playback gets all crackly. I have to stop and restart. No big thing, but I wasn't sure if it is working for others and there is just something I'm doing wrong.