Is it posssible to make two (or more) specific layers active at once?

[davidf]

I have found it necessary to have an Time Instances layer and a Spectrograph layer active at the same time. Is there a way to select two specific layers and make them active at the same time? I  need to see the pitches and the time instances at the same time. It is the time instances I'm trying to edit, I just need the spectrograph data to make sure I'm at the right place in a large orchestral score.

thanks,
davidf