code: def build_wxsfile_default_gui(root):
      
      factory = Document()
      Product = root.getElementsByTagName('Product')[0]
  
      UIRef   = factory.createElement('UIRef')
      UIRef.attributes['Id'] = 'WixUI_Mondo'
      Product.childNodes.append(UIRef)
  
      UIRef   = factory.createElement('UIRef')
      UIRef.attributes['Id'] = 'WixUI_ErrorProgressText'
      Product.childNodes.append(UIRef)
docs: This function adds a default GUI to the wxs file