You're probably thinking of OS/2 1.1, which was very close to Windows 2.0 in look and feel, i.e. flat and mostly monochrome, although it had a proportional syst

You're probably thinking of OS/2 1.1, which was very close to Windows 2.0 in look and feel, i.e. flat and mostly monochrome, although it had a proportional system font where Windows still used monospace (Fixedsys). Comparison: http://toastytech.com/guis/os211cpl.png http://toastytech.com/guis/os211cpl.png https://www.cs.umd.edu/hcil/muiseum/systems/win2/01.gif https://www.cs.umd.edu/hcil/muiseum/systems/win2/01.gif OS/2 1.2 added the style that would become Windows 3.0's, with beveled buttons and so on, while Windows 3.0 upgraded to the proportional font (System) that OS/2 had been using.