Amiga E has a simple wrapper for gui generation called EasyGUI. It's not as pretty as ClassAct/ReAct or MUI but it gets the job done in a hurry. Look on the Aminet for examples of any of these.
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For an easy way to make self-contained applications with MUI-Like configurability for free you might consider
Feelin' which lets you set up most of your GUI and Application in general using an XML script. It's a really small library too!
