int error = DoVideoBitMapMethod(APTR handle, int method, APTR data);
method and a data parameter. The contents of the data parameter depend on
the specified method.
The following methods are currently recognized:
HWVBMMTHD_SETBLEND:HWVBMMTHD_SETBLEND is passed, the data parameter will
just be an int that is set to True or False to enable or disable the blend flag.
DoVideoBitMapMethod() is an optional API and must only be implemented if HWSDAFLAGS_VIDEOBITMAPADAPTER
has been passed to hw_SetDisplayAdapter(). See hw_SetDisplayAdapter for details.