Is there an application for Ubuntu, that would behave like KidKeyLock for Windows?

That is, upon activation, it prevents any keypress from working, until a specific sequence ("password") is typed, but without locking the screen or mouse.

The point of this is to allow a kid (baby/toddler) to pound away on the keyboard, but leaving the the screen open and mouse activity unlocked, allowing the parent to browse Faceb AskUb Very Important Parenting information sites at the same time.

Related: If there are no such applications, any idea how difficult would it be to code one with Python? (If this is the case, I will of course ask further from StackOverflow...)