must generate the hevea version of the manual (for the WEB site).

grdev and the if bg_color <> white should be reintroduced for
optimisation ?

window_id should always return an int32 value.
must review completely the get set remember_mode and display_mode
machinery to provide with_screen_only


Grdev.draw_ps -> Grdev.draw_ps_file
See why clean_ps_cahe is a synonyme of Drawimage.clean_cache

Revoir aussi le reference events qui devrait être locale aux fonctions
qui l'utilisent.

See also save_rectangle, restore_rectangle.

Misc.get_suffix useless ???

-- ": ..." for options should be "  ..."
DONE -- (* int_of_float *) should be empty
