Would it be possible to add the option to auto-hide the sidebar? This would mean that when your mouse is not near the left hand side, it would slide completely out of view, maximising browser/tab space. Bring your mouse near the left hand side (or swipe your finger left to right near the left edge on a tablet) and the sidebar will slide out to be visible and usable again....
As a committed Opera user since the days of v3.2 (on 3330), I would agree with user 'duyfk3n' that to auto-hide the sidebar would be terrific. In my opinion, I think the dimmed sidebar when not pinned spoils the general outlook of the start page. Users could then have the option of pinning it, or not.