This would be in the category of wishlist. Adding articulations in the Key editor isn’t particularly efficient. What if, we could stay in the project window, select a track, position the playback cursor, open Inspector>Expression Map and just click on the required expression there and drop it in. I could quickly go through a track this way but just observing the content of the track.
Hi,
Add the Feature Request tag, please.
If only the million clicks I’ve done on the expression map tab within the project Windows had been helpful. 
That’d be very very useful to me. I don’t know how that could be implemented, maybe just changing the articulation at the point in time where playback cursor is located?
Anyway, +1!
Where do I add the Feature Request Tag, I’d be happy to do it.