INT 15 - TopView - SEND MESSAGE - "LEN" - GET OBJECT LENGTH
        AH = 12h
        BH = 09h
        BL = object
            00h handle in DWORD on top of stack
                window: get chars/line
                timer: get 1/100 seconds remaining before timer expires
                mailbox: (DV/X) get number of bytes queued to mailbox
            01h get number of chars/line in current task's default window
            0Ch (DV 2.26+) get chars/line in window owning handle on top of stk
            0Dh (DV 2.26+) get chars/line in parent task's window
Return: DWORD on top of stack is length