This nifty app has helped me tremendously. My trusty old Apple Extended Keyboard started acting up: the left Shift key tends to mysteriously 'stick', preventing me from logging in. That's just part of the trouble; typing in Caps Only is no good. Thanks to Seil I was able to disable the left Shift. Typing is a bit awkward without it, but no more trouble logging in!
Seil is excellent, it is very stable and offers a lot of control over improving the keyboard bindings. I use it mainly to convert my unused CAPS LOCK key into an ENTER key, being left handed I can enter easier this way. It is frequently updated by a very responsive developer, thank you!!!