> I can't figure how to add a scrollbar to a canvas; here is my code:
> 
> ------------------------------------
>  
> open Tk
> open Printf
> 
> let _ =
>   let win = openTk() in
>   let c = Canvas.create win ~width:2560 ~height:100 in
>   let s = Scrollbar.create win ~orient:`Horizontal in
> 
>   (* draw clearer and clearer gray strips on the canvas. *)
>   for i = 0 to 255 do
>     let color = `Color (sprintf "#%02x%02x%02x" i i i) in
>     ignore(Canvas.create_rectangle c ~x1:(i*10) ~x2:(i*10+10) ~y1:0 ~y2:99 
>       ~fill:color)
>   done ;
> 
>   Canvas.configure c ~xscrollcommand:(Scrollbar.set s) ;
>   Scrollbar.configure s ~command:(Canvas.xview c) ;
> 
>   place c ~x:0 ~y:0;
>   place s ~x:0 ~y:100 ~relwidth:1.;
>   Wm.geometry_set win "300x125" ;
>   mainLoop()
> 
> ------------------------------------

You should use the ~scrollregion option:
  Canvas.create win ~width:300 ~height:100 ~scrollregion:(0,0,2560,100)

Then you don't need the Wm.geometry_set anymore.

---------------------------------------------------------------------------
Jacques Garrigue      Kyoto University     garrigue at kurims.kyoto-u.ac.jp
		<A HREF=http://wwwfun.kurims.kyoto-u.ac.jp/~garrigue/>JG</A>