Though it's great having an almost boundless customizability, it's a little cumbersome having to open panel layout editor and then open panel settings again to adjust small settings every time. How about adding a drop-down menu to "Configure Layout" button (like v2.5 with a small triangle icon next to it) and show some quick settings people use most often? It could show tabs bar settings, column browser layout, AZ bar, show/hide left/right main panel, player control location, etc. Also it could display show/hide headbar setting and panel settings for the selected tab.