INT 16 - PC Tools v5.1+ DESKTOP API - INVOKE NOTEPAD EDITOR
        AX = FFF6h
        DS = segment of editor buffer structure (see below)
        BX = ???
        DX = segment of window parameters structure (see AX=FFB5h)
Return: ???
Note:   available only when popped up

Format of editor buffer structure:
Offset  Size    Description
 00h    WORD    offset of current cursor position in buffer segment
 02h  2 BYTEs   ???
 04h    WORD    offset of beginning of file data in buffer segment
 06h 10 BYTEs   ???
 10h  N BYTEs   ASCIZ name of file being edited