The whole world of GUI programming was based on OO.
The Xerox Star was introduced in 1981 https://en.wikipedia.org/wiki/Xerox_Star
Apple's Lisa was introduced in 1983. https://en.wikipedia.org/wiki/Apple_Lisa
With it, Lisa Toolkit and Clascal (Pascal with Classes) http://www.mirrorservice.org/sites/www.bitsavers.org/pdf/app...
The Mac in 1984 https://en.wikipedia.org/wiki/Macintosh_128K
MacApp in 1985 https://en.wikipedia.org/wiki/MacApp
The Tektronix 4404 running Smalltalk, also 1984 http://www.wirfs-brock.com/allen/files/tek/4404-Flyer.pdf
The Amiga and Atari ST in 1985.
Windows was at 2.0 in 1987.
Heck, the NeXT cube had been introduced by fall of '88.
https://en.wikipedia.org/wiki/NeXT_Computer
The whole world of GUI programming was based on OO.