This document applies to Avid Studio and Studio 16.
For certain effects like Picture in Picture it might be useful to see other timeline tracks while you are in the Effects Editor. You can do this by enabling toggling the Solo button.
While it is highlighted, the current clip in the Navigator is shown in isolation when previewed, without taking into account the effect of any clips either above or below it on the timeline. While the button is not highlighted, all timeline tracks can contribute to the preview.