I'll take filled rounded corners over the window border bulge atrocity seen in IRIX.

Also keep in mind IRIX (and most classic desktops) assumed 72 DPI displays rather than 96 DPI displays. That means when you view a screenshot or render them unadjusted they look 75% the size they did back in the day. Still plenty denser in many ways... just not as much as loading it up on a modern "96 DPI is 100%" screen would imply.

I miss real window borders that you could see and drag—what a concept.