You can also open a separate score editor window, select the region you want to view, and then turn off the link button (so it turns gray). Now what you see in the score display will not change even if you select a new region (or record a new region).
You can have multiple score editor windows open by using the "Open Score Editor..." key command.
This trick also works in the 'embedded' score editor window in the arrange area.
And if you have a score display in the embedded score editor that you want to make a separate score window from, grab the "Score" tab (at the bottom of the arrange area) and drag upwards. The score editor will kind of tear away from the arrange area and create a separate score editor window.