Can't change the layout of alternatives keys show on android keyboard

I want to change the default layout which Android uses for show the alternative keys when performs a long-press on a key. Keys have an attribute "android:popupKeyb开发者_Go百科oard" used for define the layout of the alternative key list (which could be a Keyboard reference) but when I use it the Android's default layout still appears. Is possible to change or override this layout?

This isn't possible without writing your own software keyboard. You'll find a good starting point in Creating an Input Method.