option 1:
in the xml file:
<!-- using attribute "id" to select a widget -->
<textfield id="tf1"></textfield>
<button onaction="act(#tf1.text)"></button> <!-- the textfield's content will be used as an argument to the action "act" -->
option 2:
in Frame's method
public onMessage(String identifer,Object[]arguments){
Widget wig=FrameFocus.getWidget("tf1"); //get the widget by hand
}