I think you will be alright if you use my suggestion above. Just make sure you change 'World' to your world name in step # 2 and eliminate all instances of 'World.' in step # 3. And if you do not have a 'private String btnText;' in your button object classes, add them and make them equals to the button text. Then in step # 2, you should have in brackets '{ World.lastButton = btnText; }'. Again 'World' should be 'TextWorld', if that is the name of your world; if not, it should be the name that you gave your world.
How do I access the '.png' image that you mentioned?