No, that is by design.
Really? For what reason?
Surely it would be useful to make that an option so that those of us with 2 monitors (or even a single monitor) can still watch/listen to the playback while doing something else at the same time?
1. It is very unwise to do something else during an editing session. Either you edit or you don't.
2. Most computers do not have the horsepower.
3. If you insist on doing something else, there is no need for playback to continue, since you can't concentrate on two or more things at the same time.
4. If you want to play a timeline and do something else at the same time, use a player, not an editor.
5. If you want to do something else during an editing session, use a separate computer.
6. An editing program needs all the computer resources available. If you willingly steal that from an editor by doing something else, the editor can no longer work satisfactory.
Along with the audio control surface, this would be a VERY welcome feature in my opinion.
For those concerned about CPU drain, it should be possible to turn this feature on or off.
When I'm editing fluidly in FCP I do in fact leave the timeline playing whilst I go to other windows to select an effect, tweak a bit of audio or even move to a different app - there's nothing unusual about this at all.
Ultimately we all have our own ways of editing, but trust me, when you've been used to (and seen the benefit of) an NLE 'feature' you really miss it when the manufacturer chooses not to include it.
Thanks, Adam, by the way, how to you 'enable this feature' in FCP as I have that as backup, but much prefer Premiere Pro now?