Possible to remap CapsLock to emulate the "French - Numerical" behavior on a U.S qwerty keyboard I would like to remap the capslock key to behave as such:


When Off : 


letters are lowercase
numbers are not active (symbols characters are active)
other symbols (not on the numbers row) behave normally (as if shift was up)

When ON: 


letters are uppercase
numbers are active
other symbols (not on the numbers row) are inverted (as if shift was down)



It is the behavior from the "French - Numerical" layout, but I need this on a U.S. keyboard.
Not natively, as far as I'm aware.

Though I don't think it'd be easy, I guess you could use an app such as Ukulele. I suggest the stable 2.2.8 version, since the 3.0 beta might crash when changing modifier keys.


Download Ukulele
Change your keyboard layout to French - Numerical ( > System Preferences > Keyboard > Input Sources)
In Ukulele: File > New From Current Input Source (Which is why you changed to French - Numerical in the previous step). After this you can change back to the regular keyboard layout.
Essentially change all of the keys to match the English QWERTY.
Save your new layout in your Library folder > Keyboard Layouts (Accessable by pressing ⇧+⌘+G and typing in "~/Library/Keyboard Layouts" and clicking Go)
Log out and log in again an switch to your new fancy keyboard layout


I think this is the way to go simply because Apple probably did some fancy trickery to make this work for the French layout, so if you base it off of that, you might be able to "trick" the system into accepting the new one.

Note: Since we're not entirely sure this'll work, I'd recommend only changing a couple of keys to be begin with, as a "proof of concept" (Then, obviously, if it works, simply finish the layout and repeat step 5 and 6).

Good luck!