void draw_line(frontend *fe, int x1, int y1, int x2, int y2, int colour);
void draw_polygon(frontend *fe, int *coords, int npoints,
int fill, int colour);
+void draw_circle(frontend *fe, int cx, int cy, int radius,
+ int fill, int colour);
void clip(frontend *fe, int x, int y, int w, int h);
void unclip(frontend *fe);
void start_draw(frontend *fe);