Created attachment 247796 [details] Visual of how a Button could look like that toggles the Navigation Sidebar Collapse and expand functionality of "Navigation Sidebar" is mostly controlled by Toolbar-Items. Clicking on a Toolbar-Item collapses or expands the Sidebar. This functionality is not intuitive because visually the Toolbar stretches across the whole vertical area which implies that the Toolbar-Items would change the whole area below the Toolbar. For that reason I'd like to introduce a new Toggle-Button that triggers "collapse" and "expand" of the left Sidebar. I would follow Xcode design principles and add a Button that looks similar to the Button that toggles the "Debug area". Depending on your feedback, I could add follow-up bugs that could introduce similar Buttons for the "Details sidebar" and "Quick console". I'd be interested in implementing that functionality if possible.
<rdar://problem/20028528>
Thanks for the interest and mock up Tobias. We had these buttons in Safari 6 and based on user feedback we switched to the new toolbar interface with the toggle buttons. I haven't seen other complaints about the new UX of these buttons. I don't think we should bring the sidebar toggles back. Note, we still allow double click on the divider to collapse.