input handling doesn't handle conflicts between game and text input

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If the user has mapped a regular key to some game function, such as say "a" and 
then types text into an input box containing "a", it will result in both a text 
input event and a regular game event. This is caused by game buttons being 
handled by GUIScreen directly, bypassing the regular GUI focus handling.

Original issue reported on code.google.com by grum...@gmail.com on 16 Sep 2011 at 6:05