Slightly F-keyed off

[Richmond]

Right . . . I'm a bit like Hank Wangford: In search of the lonesome yodel.

Not really; but I am in search of the lonesome modifier key which is 
going to be 'totally transcendental'
and rise above the petty materialism (pace maya-tattva) of types of 
computer and types of operating system.

So, I would be most grateful if a Windows mages could tell me:

1. What they think about my using an F-key as a keyboard modifier.

2. What F-keys are not otherwise engaged.

Likewise for Macintosh and Linux.

For years (well from 1992 to 2004) while I was a Macintosh monomaniac, I 
could not
understand why one could not access four keyboard layouts with Windows 
as one could
with Macintosh OS 7 - 9.

I have been mucking around with rawKeyDowns, and on "modern" systems 
(just love that word 'modern', about as useful as a bucket of quicksand) 
the ALT and SHIFT-ALT combos don't send different keyDowns when letter
keys are pressed while they are depressed.

Having 'failed' with the altKey, and subsequently with the ctrlKey, 
eschewing the capsLockKey, and still
being in search of a second keyboard modifier key that will be truly 
cross-platform I am rapidly
getting desperate and becoming a cross-patch.

Richmond.