Really small is still too much space on a laptop screen. I think it's more of three decades of muscle memory from other apps like Photoshop and QuarkXPress. Putting magnification level in a consistent spot where it's always visible and editable is good UX. Affinity puts a non-editable magnification level in the Toolbar, an editable magnification level in the Context Bar but only when the Zoom tool is selected, and an editable magnification level in the Navigation panel which is often hidd