The color of the crosshairs is color2().
Fl_Positioner(int x,int y,int w,int h, const char *l);
float xvalue() const {return xvalue_;}
float yvalue() const {return yvalue_;}
void value(float *a,float *b) const {*a = xvalue(); *b = yvalue();}
int xvalue(float);
int yvalue(float);
int value(float,float);
void xbounds(float, float);
void ybounds(float, float);
void xbounds(float *a, float *b) const {*a = xmin; *b = xmax;}
void ybounds(float *a, float *b) const {*a = ymin; *b = ymax;}
void xstep(float a) {xstep_ = a;}
void ystep(float a) {ystep_ = a;}
void when(char a) {when_ = a;}
char when() const {return when_;}