interface screen : public canvas
  {
    screen(char* p,char* options = "");
    screen(widget* w,char* p,char* options = "");
    virtual ~screen();
     
    int line(int x1,int y1,int x2,int y2,char* options = "");
    int line(char* linespec,char* options = "");
    int oval(int x1,int y1,int x2,int y2,char* options = "");
    int circle(int x,int y,int r,char* options = "");
    int polygon(char* linespec,char* options = "");
    int rectangle(int x1,int y1,int x2,int y2,char* options = "");
    int square(int x,int y,int r,char* options = "");
    int bitmap(int x,int y,char* bitmap,char* options = "");
    int text(int x,int y,char* txt,char* options = "");
  
    void move(int id,int x,int y);      // move item
    void move(char* fig,int x,int y);   // move figure
  
    void del(int id);                   // destroy item
    void del(char* fig);                // destroy figure
  
    void tag(int id,char* tg);          // add a tag
    char* tags(int id);                 // which tag ?
     
    int overlapping(int x,int y);       // which item on (x,y)
    char* items(int x,int y);
  
    void postscript(char* fn);          // generate postscript
  };