This is currently done in the Elements tab sidebar, and it makes switching between sidebars/filers much faster.
Created attachment 313368 [details] Patch
Switching tabs is also on mousedown; this change makes it more consistent.
Comment on attachment 313368 [details] Patch r=me. Please add a comment to the change log explaining the motivation for the change. I would mention consistency with the tab bar, etc.
Created attachment 313471 [details] Patch
Comment on attachment 313471 [details] Patch Clearing flags on attachment: 313471 Committed r218623: <http://trac.webkit.org/changeset/218623>
All reviewed patches have been landed. Closing bug.