textbox (G4P GUI BUILDER)

hello guys.

I am trying to save the value of textbox in a variable, I created textbox with the help of "G4P GUI BUILDER", so how can I store the typed value in variable.

/** =========================================================
 * ====                   WARNING                        ===
 * =========================================================
 * The code in this tab has been generated from the GUI form
 * designer and care should be taken when editing this file.
 * Only add/edit code inside the event handlers i.e. only
 * use lines between the matching comment tags. e.g.

 void myBtnEvents(GButton button) { //_CODE_:button1:12356:
     // It is safe to enter your event code here
 } //_CODE_:button1:12356:

 * Do not rename this tab!
 * =========================================================
 */

public void textfield1_change1(GTextField source, GEvent event) { //_CODE_:txtName:280460:
  println("txtName - GTextField >> GEvent." + event + " @ " + millis());
} //_CODE_:txtName:280460:

// Create all the GUI controls.
// autogenerated do not edit
public void createGUI(){
  G4P.messagesEnabled(false);
  G4P.setGlobalColorScheme(GCScheme.BLUE_SCHEME);
  G4P.setCursor(ARROW);
  surface.setTitle("Sketch Window");
  txtName = new GTextField(this, 148, 145, 160, 30, G4P.SCROLLBARS_NONE);
  txtName.setOpaque(true);
  txtName.addEventHandler(this, "textfield1_change1");
}

// Variable declarations
// autogenerated do not edit
GTextField txtName;

thanks