INT 15 - DESQview v2.20+ - internal - ???
        AX = DE18h
        BP = function number
            high byte must be 10h
            low byte is function
                00h set ???
                    BL = ???  (00h-10h, video mode???)
                    BH = value to store
                03h set ???
                    BL = ??? (stored in driver)
                0Ah get ???
                    ES:DI -> 18-byte buffer to hold ???
Note:   calls video driver (NOP for Hercules driver,probably CGA and MCGA also)