developer9i: Web Forms Runtime: usesdi=YES: option not working?

..on developer 6.0 web forms it worked nice.

cut from developer9i help below:

Single Document Interface
Although MDI is the default system of window management during Forms Runtime, Forms Developer also provides support for an SDI root window on Microsoft Windows. You can set the system of window management to SDI by specifying the USESDI command line option. When SDI is enabled, calls to the FORMS_MDI_WINDOW constant returns NULL for the MDI window handle. There is no multiple interface root window, MDI toolbars exist in parent windows, and MDI menus are attached to each window.

USESDI (Web Forms Runtime)
Description Use single document interface (SDI) system of window management during a Web Forms Runtime session. There is no multiple document interface
(MDI) root window. MDI toolbars exist in parent windows and menus will be
attached to each window. Calls to the FORMS_MDI_WINDOW constant returns NULL as the MDI window handle when usesdi=YES. Option Name None Default No USESDI
(Forms Runtime) Examples

http://myserver/forms90/f90servlet?form=MODULE1.fmx&usesdi=YES

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