No. They work as you expect, but @manojm321 uses the One True Editor, which has different bindings. Control-K should kill to the end of the line. Control-y should yank text out of the kill buffer and on and on.
@manojm321, it’s not ruby you need but javascript and ember. You can do it in a component, I think. Oh, the shortcuts I added were not to the composer but to the main interface. I still think it’s possible, but I don’t know that I know where an example is.
You can look for theme components that add to the composer and/or search the source for, maybe, paste.