fix typo in Button widget
fix typo in Button widget

brunano21/deliteful,cjolif/deliteful,tkrugg/deliteful,kitsonk/deliteful,harbalk/deliteful,harbalk/deliteful,EAlexRojas/deliteful,tkrugg/deliteful,kitsonk/deliteful,EAlexRojas/deliteful,brunano21/deliteful,cjolif/deliteful