Is it possible to set caps lock to switch between inserting numbers and the symbols they normally trigger when one holds shift?
e.g. when you normally press the 9 key, you get a ( unless caps lock is on.
I tried adding this line to my layout file, on /usr/share/X11/xkb/symbols:
key <AE05> { [ percent, 5 ] };
This effectively switches the 'normal' and 'shift' meanings, but it won't work on caps lock - only on shift.