Frequently when using the timelines I'll find myself struggling to get back to the overview view. Often I'm in the overview view, click on a line number to see a source code editor, click another line number to open another editor, now I want to go back to the overview view. Unfortunately I either have to go "back" a lot of times, or select and deselect a specialized timeline. Both of these are non-obvious. There should be a way to go directly to the timeline overview view.
Simon recently complained about the interaction model here, with having to click the [X] placed in an unusual place to change the content view. Not sure how to fix the [X] design since we have an implicit "overview" timeline. Instruments does not have a similar thing.