How do I make a slider in a GL program?

[Dan Severance]

  Hi,
     Are there any functions out there that define a simple slider
that can be called along the lines of:
call mkslider(slidenum,xscreen_coord,y_screen_coord,minval,maxval)
and val=read_slider(slidenum) ??
     Thanks, I'm using the GL libraries (Fortran, but I can deal with C),
on a P.I. 4D-25 soon to be 4D-35..

-------------------------------------------------------------------------
     Dan Severance

     dan at omega.chem.yale.edu
     Laboratory of Computational Chemistry
     Yale University