During playback, I can't seem to select clips, etc.  I have to stop the transport...THEN select a clip.  So...IOW I can't seem to drag a clip around during playback.  Is that correct? Using the smart tool, btw. 

It's these little items that I really need to learn, but there are only about 100 of them! ;-)

Never tried such a thing, but would make sense that it is not allowed. The audio needs a buffer and if you grouped several clips and began moving them over the now time the audio engine would have a seizure.

what I'm typically doing is drag/copy...or lining stuff up with the Quantize turned off, to get a better "feel" on my humanoid MIDI parts.   So...in effect, I'm "out of the way" of the NOW time.  ....sometimes!   Yeah, I can see yanking a clip out from under the audio engine and making it puke.  

However.....if the clip is already highlighted... I can move it around.  I at least figured that out on my own!
 
you just can't highlight something with things in motion   You just pre-highlite   (that's my new word for the day)