Hello, Chris Mckevitt,
Very easily, indeed ! Instead of pressing the Tab key, Chris, just hold down the Alt key and hit, successively, on the Numeric keyboard, the two 0 and 9 keys => The auto-complete box is, then, closed and a single tabulation character ( \x09 ) is inserted, at the caret’s position :-)) Et voilà !
I verified that it’s OK, for, both ,completion of functions AND completion of words
Of course, it’s not as straight as hitting an unique key, but just consider it as a work-around !
Best Regards,
guy038