Just a quick update, from a computer forum
This appears to be where the code completion appears to have perhaps originated.. as expected, not Microsoft (Quel Surprise).
Looking Glass Software's Alice Pascal, a syntax directed editor,
interpreter, and debugger for teaching Pascal, had context sensitive
code completion. It shipped for DOS PCs and CEMCORP ICONs in 1985,
and for Atari STs in 1986. You can read about it, and download the PC
and ST versions of Alice, source code and all, from Brad Templeton's
Alice Pascal page at
http://www.templetons.com/brad/alice.html.