[Wowfunhappy]

> QuickLook remains one of the few examples of a generic extensible document reader in modern operating systems.

...were there other ones in classic operating systems? QuickTime <= 10.2 did let you install third-party components (I wrote one recently), but what else was there?

[mixmastamyk]

The Amiga pioneered this with datatypes.

[kitsunesoba]

There was OpenDoc on classic Mac OS, and I think maybe COM on the Microsoft side of the fence? Not as well versed on Windows stuff though so that may be a misread on my part.