Set object bits

        Entry:
          AH = 12h
          BH = 0Ah
          BL = object
              00h handle is DWORD on top of stack
                  Window: write characters and attributes
                  Timer: start timer for specified interval
                  Pointer: set control flags
              01h write characters and attributes to task's default window
              02h send message/status by value to mailbox
                  (task's handle on stack)
              03h send message/status by value to current task's
                  default mailbox
              04h set control flags on KEYBOARD object
                  (handle on top of stack)
              05h set control flags on task's default KEYBOARD object
          STACK: (if mailbox) DWORD status
                              DWORD length of message
                              DWORD address
                 (if timer)   DWORD duration in 1/100 seconds
                 (if window)  DWORD count of characters
                              DWORD address of characters
                              DWORD count of attributes
                              DWORD address of attributes
                 (otherwise)  DWORD bits to set

        For keyboard objects, the bits have the following significance:

          Bit 15 reserved, can't be set
          Bit 14 unused
          Bit 13 reserved, can't be set
          Bit 12-5 unused
          Bit 4  filter all keys (used with handler established by SETESC)
          Bit 3  program continues executing while input in progress
          Bit 2  insert mode active
          Bit 1  keyboard is active
          Bit 0  keyboard is in field mode

        For pointer objects, the bits have the following significance:

          Bit 15 reserved, can't be set
          Bit 14-8 unused
          Bit 7  mouse pointer is hidden while in window
          Bit 6  get messages even if window not topmost
          Bit 5  get messages even if window not foreground
          Bit 4  mouse button must be held 1/2 second before it "clicks"
          Bit 3  pointer position is relative to screen origin, not window origin
          Bit 2  send message on button release as well as button press
          Bit 1  unused???
          Bit 0  send message only on button activity, not movement
                 DV-specific, and INT 15h/AX=DE0Fh must have been called first