interface scale : widget { 
  
      scale(char* p, char* options = "");
      scale(widget* w, char* p, char* options = "");
  
      void text(char* s);                        // text to display
      void from(int n);                          // begin value
      void to(int n);                            // end value
      int get();                                 // gets the value
      void set(int v);                           // sets the value
  
    protected:
      install(binding*, char* args);
    };