There’s a big secret hidden in Apple’s latest beta by Ben Geier @FortuneMagazine August 4, 2015, 5:06 PM EDT E-mail Tweet Facebook Linkedin Share icons A new screen size option for Apple iMac desktops with Retina displays may soon be available, according to a report from 9to5Mac.com. The beta version of Apple’s upcoming operating system apparently includes several references to a new 21.5-inch screen size for the Retina display desktop computer. This would go along with the currently existing 27-inch option. Rumors have already been swirling about this possible new addition. We’ll likely know more later this year, as Apple tends to make big product announcements in the fall.