The Microsoft engineer who gave us Word's red squiggle dies

Tony Krueger, a longtime Microsoft developer, has died. While Wikipedia credits him mainly for porting the game Chip’s Challenge to Windows—a feat he pulled off by reverse-engineering the MS-DOS version without access to its source code—his most far-reaching work was on Microsoft Word, which he shipped across more versions than likely anyone else, from 1.0 through 6.0 and beyond, including the OS/2 and Mac editions.

Krueger’s signature contribution was reinventing spell check. Early Word required users to manually launch spell check and wait through a blocking, one-error-at-a-time review; even the later “auto” mode interrupted foreground work, prompting many people to disable it. He made the checker run unobtrusively in the background and flag suspected mistakes inline with the now-ubiquitous red squiggles, followed later by green squiggles for grammar.

That small interface idea became a near-universal standard, appearing in virtually every word processor and far beyond. Krueger did it first, even earning fan-mail-style praise from Penn and Teller and a cameo of his feature in “Weird Al” Yankovic’s Word Crimes video—a fitting legacy for a piece of UI almost everyone has relied on without knowing who built it.