private void fillComboBox() {
   myComboBox.removeAllItems();
   for (XExpression expression : getRecentExpressions()) {
     myComboBox.addItem(expression);
   }
   if (myComboBox.getItemCount() > 0) {
     myComboBox.setSelectedIndex(0);
   }
 }
  @Override
  protected void doSetText(XExpression text) {
    if (myComboBox.getItemCount() > 0) {
      myComboBox.setSelectedIndex(0);
    }

    // if (myComboBox.isEditable()) {
    myEditor.setItem(text);
    // }
    myExpression = text;
  }