All of this really depends on what you are doing exactly.
If the text is in a uservar, you can add a line like the following to a button:
addCommand "clearUserVar VarName"
Or if not using a UserVar for your text widget, you could add a ShowCondition with UserVarSet on the text widget, add a User var to use, and the buttons set the uservar to 1 for the text it wants you to see, and sets the uservars of the others to 0.
Depths of Peril, Kivi's Underworld, Din's Curse, Drox Operative, Zombasite, Din's Legacy, & Drox Operative 2