INT 15 - TopView - SEND MESSAGE - "ADDTO" - WRITE CHARS AND ATTRIBS TO WINDOW
        AH = 12h
        BH = 0Ah
        BL = window to write to
            00h window handle is DWORD on top of stack
            01h current task's default window
            0Ch (DV 2.26+) default window of task owning handle on top of stack
            0Dh (DV 2.26+) default window of parent of current task
        STACK:  DWORD count of attributes
                DWORD address of attribute string
                DWORD count of characters
                DWORD address of character string
Notes:  if one string is longer than the other, the shorter one will be reused
          until the longer one is exhausted
        the cursor is left just after the last character written