Write panel to window

        Entry:
          AH = 12h
          BX = 0400h
          STACK: DWORD handle of panel object
                 DWORD window's handle or 0
                 DWORD length of panel name
                 DWORD pointer to panel name

        Return:
          STACK: DWORD handle of created keyboard or 0
                 DWORD handle of window which was used

        Notes:  Status of APPLY may be checked with STATUS message panel
                MUST have the following format:

         First byte must be 1Bh (i.e. must start with a stream)
         First opcode in stream must be E5h
           Single byte arg of opcode is interpreted thus:
              bit 7  \  11 means create new window
              bit 6  /  10 means create new field table for existing window
                        01 means use existing window and field table
              bit 5 if set, panel contains a field table
                        (creates a new keyboard and puts it in field mode)
              bit 4 if set, panel contains input fields
              bit 3 if set, panel contains select fields but no input fields