Keep search active when switching documents in sidebar

Often I search within a project, then realize that I need to expand the search scope. But when I click the sidebar, the search terms disappear. I’d prefer that the search remain active. Like this guy:

The Go Home key is helpful but it still necessitates retyping the search.

In Finder and Apple Mail, you can switch from searching the current folder to searching the entire Spotlight scope / All mailboxes, without needing to re-enter your search terms. In a program like TP, where complex searches are a key piece of functionality, it seems even more important to offer this capacity.