http://en.wikipedia.org/wiki/Input_method
Notice strings need to be "edited inline" so to speak and confirmed by hitting Enter. It's sort of like "inline renamig" in Windows Explorer if you will.
Now this function provided by Microsoft needs to be supported if programs are claimed to support unicode. Text editors are a good exmaple. Nowadays majority of them support unicode. So authors of those text editors need to and are able to support this kind of input method even though they don't know a thing about relevant languages.
Here is an exmaple in which the lack of this support is demonstrated.



Can you see it's not "inline" and Microsoft comes in to rescue?