public void setSelected(boolean b) {
   super.setSelected(b);
   if (selected) {
     if (!(exprFieldX.hasFocus() || exprFieldY.hasFocus() || exprFieldZ.hasFocus())) {
       exprFieldX.requestFocusInWindow();
       fireCaretUpdate(exprFieldX);
     }
   }
 }
 public void setMother(Function f) {
   super.setMother(f);
   exprFieldX.setText(f.getExpression()[0]);
   exprFieldY.setText(f.getExpression()[1]);
   exprFieldZ.setText(f.getExpression()[2]);
 }