I would also be very happy with functionality proposed by aef6259, especially "button on the bottom left of the preview section" for example after close button or on the right to prevent mistakes, because a I'm putting almost all songs directly from preview mode to live mode - and such a button would save much time (it takes some time to find again the song title on the list, right click, find second position and then left click - if you get the song title when it's started to singing) and mistakes when in song list are many songs with similar titles.
I hope that I show the need of this feature - of course in my case (I think that, there are more people, whom such a button would help, and it won't disturb other how don't need it)