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─────Run-Time Library───────────────────────────────────────────────────────
 
     The _wopen function opens a QuickWin window, returning a file
     handle to the window. This routine is used only in QuickWin
     programs; it is not part of the Windows API. For full details
     about QuickWin, see Chapter 8 of the Programming Techniques
     manual.
 
     The _wopeninfo and _wsizeinfo structures, declared in IO.H, are
     used to pass window initialization information, including the
     window's initial size and position on the screen. You can pass
     NULL for the _wsizeinfo argument to accept QuickWin size and
     positioning defaults, or you can declare a variable of type
     _wsizeinfo and fill in its fields with initial values. You must
     declare a variable of type _wopeninfo and fill in its fields.
 
     For both the _wopeninfo and _wsizeinfo variables, set the _version
     field to _QWINVER, which is defined in STDIO.H and IO.H.
 
     For the _wopeninfo variable, assign a null-terminated string to
     the _title field containing the desired window title. You can
     also optionally set the size of the window's screen buffer in the
     _wbufsize field. The default is 2048 bytes, but you can pass
     some other number or the value _WINBUFINF. The value _WINBUFINF
     imposes no limit on the buffer size.
 
     For the _wsizeinfo variable, if you choose to pass size
     information, assign one of the following values to the _type field:
 
     Value            Meaning
 
     _WINSIZEMIN      Minimize the window
     _WINSIZEMAX      Maximize the window
     _WINSIZECHAR     Use character coordinates for the window size
 
     If the type is _WINSIZECHAR, you must supply the _x, _y, _h, and
     _w values in the remainder of the structure. They specify the
     upper-left corner and the height and width of the window (in
     characters).
 
     The _wopen function is a low-level I/O call. It accepts the
     following access flags: _O_BINARY, _O_RDONLY, _O_RDWR, _O_TEXT,
     _O_WRONLY.
 
     These flags can be combined with the bitwise-OR operator (|). See
     _open for additional information about the flags.
 
     Unlike the _open function, _wopen does not accept the _O_CREAT,
     _O_TRUNC, or _O_EXCL flag. Using one of these flags results in an
     error.
 
     Return Value
 
     If successful, _wopen returns a QuickWin file handle. A return
     value of -1 indicates an error; errno is set to one of the
     following values:
 
     Value       Meaning
 
     EINVAL      An invalid <oflag> argument was given
     EMFILE      No more file handles available (too many open files)
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