android keyboard popout, how is it made?

I'm trying to make an android keyboard and was wondering how to make a letter pop out, when it is hit.

I tried using a custom dialog, but it tot开发者_如何学Cally would not work within InputMethodService.

crashes with:

ERROR/AndroidRuntime(17125): at 
    keyboard.rob.com.TotalKeyboard$3.onTouch(TotalKeyboard.java:527)

when dialog.show(); is called.

So, supposedly some other method would be needed.

I have the sample keyboard code, but couldn't find the place where it show a popout letter. Yet I'm sure it doesn't use dialogs.

Any ideas how to achieve that?

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Could be using a FrameLayout with a drawing canvas stacked at the nearest index. When someone selects a letter, it draws that letter on the top index of the frame layout.