Get panel file directory

        Entry:
          AH = 12h
          BX = 0300h
          STACK: DWORD handle of panel object

        Return:
          STACK: DWORD length of directory
                 DWORD address of directory

        Format of panel file:

        Offset        Size    Descriptoin
         00h  2 BYTEs   C0h C3h
         02h    BYTE    number of panels in file
         03h    for each panel in file:
                    8 BYTEs  blank-padded panel name
                      DWORD  panel offset in file
                      WORD   panel length
                data for panels (each consists of one or more window/query/manager
                streams)
                    first byte of each panel must be 1Bh, fifth byte must be E5h