I’m running Ubuntu on a Macbook Pro with a Retina display. By default Komodo 9 does not scale pixels based on the platform settings (e.g Settings->Display->Scale for menu and title bars). I believe this is because mozilla SDK has only just fixed this to read the platform setting in latest dev versions.
As a work around I’ve manually edited lib/mozilla/greprefs.js and changed “layout.css.devPixelsPerPx” to better value. e.g 2.0.