[gtkada] locate the C function

[yoann toussaint]

hello,
the function draw_line in the gtk-extra-plot package is implemented like 
that :

 procedure Draw_Line (Plot : access Gtk_Plot_Record;
                        Line : Gtk_Plot_Line;
                        X1, Y1, X2, Y2 : Gdouble)
   is
      procedure Internal (Plot : System.Address;
                          Line : Gtk_Plot_Line;
                          X1, Y1, X2, Y2 : Gdouble);
      pragma Import (C, Internal, "gtk_plot_draw_line");
   begin
      Internal (Get_Object (Plot), Line, X1, Y1, X2, Y2);
   end Draw_Line;

Is anyone knows how to locate the C function 'gtk_plot_draw_line'
in gtkada there is a lot of function which use C function with 
instructions like :

pragma Import (C, Internal, "C_function");

and and I don't know how to find them

thanks,
yoann