public final function getUserColor( string $name )
   {

      if ( $this->disposed )
      {
         return null;
      }

      if ( ! isset( $this->colors[ $name ] ) )
      {
         throw new ArgumentError(
            '$name',
            $name,
            'Drawing.Image',
            'There is no user color with this name defined for this image!'
         );
      }

      return $this->colors[ $name ];

   }