Use of Lock Mode
You can lock so that only the manglish->Malayalam conversion takes
place and not the Malayalam->manglish one. (You can unlock it, if you want to paste some Malayalam and convert it to Manglish).
What is the big deal about this? An example: Assume, Malayalam->manglish is not locked. If you type ,"van", to get "വന്", Manglish-Malayalam translator recognizes it as an English word, and translates it as if you typed "വാന്". In order to avoid this, you can use "van#", which will be translated as വന് in Malayalam window. So far so good. But if you click in the Malayalam window by accident, it will translate it back to "van" (and not van#) in the manglish window, which will be converted to "വാന്" (and not "വന്")!
(contributed by Umesh)