Graphics background color under Windows

[vicuna]

Original bug ID: 7745
Reporter: sampo
Status: confirmed (set by @dra27 on 2018-02-23T21:39:34Z)
Resolution: open
Priority: normal
Severity: minor
Version: 4.06.0
Category: otherlibs
Monitored by: @nojb

Bug description

Hello everybody.
I tested this program found at this address https://www.typerex.org/images/ocpwin-graphics.png

#load "graphics.cma";;

open Graphics;;

open_graph "600x600";;

• : unit = ()

draw_poly [| 30,300; 200,40; 400,190; 250,500 |];;

• : unit = ()

set_color red;;

• : unit = ()

fill_poly [| 35,300; 200,45; 395,190; 250,495 |];;

• : unit = ()
  With Windows(OCaml 4.06.0), two things are different:

1. instead of writing on the graphic window "OCaml graphics" it is
   written Chinese characters.
2. instead of the red color, the black color is displayed.
   With Linux(OCaml 4.02.3), one error:

open_graph "600x600";;

Exception: Graphics.Graphic_failure "Cannot open display 600x600".
Thank you.
(I am not sure which category I have registered, sorry if it's not the right one)

[vicuna]

Comment author: @gasche

I seem to remember that, under X11, you need to add a space before the size specification: (Graphics.open_graphics " 400x600") may work better.

[vicuna]

Comment author: @dra27

For the Windows part, I'm not seeing the black fill instead red - can you give some more details of your set-up (which Windows port, which version of Windows).

I have no idea if the characters being displayed for the window title are strictly Chinese, but ocaml/ocaml#1629 fixes the bug!

[vicuna]

Comment author: sampo

Thank you.

If I use a Cygwin terminal, the background is red.
GNU bash, version 4.4.12(3)-release (i686-pc-cygwin)

If I use a Windows Vista terminal, the background is black.
Microsoft Windows [version 6.0.6002]
Copyright (c) 2006 Microsoft Corporation. Tous droits réservés.

[vicuna]

Comment author: @xavierleroy

The mystery of the X11 geometry specification was explained.
The bad characters in the windows title should be fixed by now.
What remains is the mysterious red background under Cygwin. Actually, even the black background under Windows could be a bug -- I thought we want a white background for all ports.