OS2::Process - exports constants for system call, and process control on OS2.

- NAME
- SYNOPSIS
- DESCRIPTION

- Optional argument to `system()`
- Access to process properties
- Control of VIO sessions
- Control of the process list
- Control of the PM windows
- Control of the PM data

- OS2::localMorphPM class
- TODO
- $^E
- EXPORTS
- BUGS
- AUTHOR
- SEE ALSO

# NAME

OS2::Process - exports constants for `system()` call, and process control on OS2.

# SYNOPSIS

        use OS2::Process;
        $pid = system(P_PM | P_BACKGROUND, "epm.exe");

# DESCRIPTION

## Optional argument to `system()`

the builtin function `system()` under OS/2 allows an optional first argument which denotes the mode of the process. Note that this argument is recognized only if it is strictly numerical.

You can use either one of the process modes:

            P_WAIT (0)      = wait until child terminates (default)
            P_NOWAIT        = do not wait until child terminates
            P_SESSION       = new session
            P_DETACH        = detached
            P_PM            = PM program

and optionally add PM and session option bits:

            P_DEFAULT (0)   = default
            P_MINIMIZE      = minimized
            P_MAXIMIZE      = maximized
            P_FULLSCREEN    = fullscreen (session only)
            P_WINDOWED      = windowed (session only)

            P_FOREGROUND    = foreground (if running in foreground)
            P_BACKGROUND    = background

            P_NOCLOSE       = don't close window on exit (session only)

            P_QUOTE         = quote all arguments
            P_TILDE         = MKS argument passing convention
            P_UNRELATED     = do not kill child when father terminates

## Access to process properties

On OS/2 processes have the usual parent/child semantic; additionally, there is a hierarchy of sessions with their own parent/child tree. A session is either a FS session, or a windowed pseudo-session created by PM. A session is a ``unit of user interaction'', a change to in/out settings in one of them does not affect other sessions.

`my_type()`

  returns the type of the current process (one of ``FS'', ``DOS'', ``VIO'', ``PM'', ``DETACH'' and ``UNKNOWN''), or `undef` on error.

`file_type(file)`

  returns the type of the executable file `file`, or dies on error. The bits 0-2 of the result contain one of the values

`T_NOTSPEC` (0)

  Application type is not specified in the executable header.

`T_NOTWINDOWCOMPAT` (1)

  Application type is not-window-compatible.

`T_WINDOWCOMPAT` (2)

  Application type is window-compatible.

`T_WINDOWAPI` (3)

  Application type is window-API.

The remaining bits should be masked with the following values to determine the type of the executable:

`T_BOUND` (8)

  Set to 1 if the executable file has been ``bound'' (by the BIND command) as a Family API application. Bits 0, 1, and 2 still apply.

`T_DLL` (0x10)

  Set to 1 if the executable file is a dynamic link library (DLL) module. Bits 0, 1, 2, 3, and 5 will be set to 0.

`T_DOS` (0x20)

  Set to 1 if the executable file is in PC/DOS format. Bits 0, 1, 2, 3, and 4 will be set to 0.

`T_PHYSDRV` (0x40)

  Set to 1 if the executable file is a physical device driver.

`T_VIRTDRV` (0x80)

  Set to 1 if the executable file is a virtual device driver.

`T_PROTDLL` (0x100)

  Set to 1 if the executable file is a protected-memory dynamic link library module.

`T_32BIT` (0x4000)

  Set to 1 for 32-bit executable files.

`file_type()` may croak with one of the strings `"Invalid EXE signature"` or `"EXE marked invalid"` to indicate typical error conditions. If given non-absolute path, will look on `PATH`, will add extension .exe if no extension is present (add extension . to suppress).

`@list = process_codepages()`

  the first element is the currently active codepage, up to 2 additional entries specify the system's ``prepared codepages'': the codepages the user can switch to. The active codepage of a process is one of the prepared codepages of the system (if present).

`process_codepage_set($cp)`

  sets the currently active codepage. [Affects printer output, in/out codepages of sessions started by this process, and the default codepage for drawing in PM; is inherited by kids. Does not affect the out- and in-codepages of the session.]

`ppid()`

  returns the PID of the parent process.

`ppidOf($pid = $$)`

  returns the PID of the parent process of $pid. -1 on error.

`sidOf($pid = $$)`

  returns the session id of the process id $pid. -1 on error.

## Control of VIO sessions

VIO applications are applications running in a text-mode session.

`out_codepage()`

  gets code page used for screen output (glyphs). -1 means that a user font was loaded.

`out_codepage_set($cp)`

  sets code page used for screen output (glyphs). -1 switches to a preloaded user font. -2 switches off the preloaded user font.

`in_codepage()`

  gets code page used for keyboard input. 0 means that a hardware codepage is used.

`in_codepage_set($cp)`

  sets code page used for keyboard input.

`($w, $h) = scrsize()`

  width and height of the given console window in character cells.

`scrsize_set([$w, ] $h)`

  set height (and optionally width) of the given console window in character cells. Use 0 size to keep the old size.

`($s, $e, $w, $a) = cursor()`

  gets start/end lines of the blinking cursor in the charcell, its width (1 on text modes) and attribute (-1 for hidden, in text modes other values mean visible, in graphic modes color).

`cursor_set($s, $e, [$w [, $a]])`

  sets start/end lines of the blinking cursor in the charcell. Negative values mean percents of the character cell height.

`screen()`

  gets a buffer with characters and attributes of the screen.

`screen_set($buffer)`

  restores the screen given the result of screen(). E.g., if the file `$file` contains the screen contents, then

        open IN, $file or die;
        binmode IN;
        read IN, $in, -s IN;
        $s = screen;
        $in .= qq(\0) x (length($s) - length $in);
        substr($in, length $s) = '';
        screen_set $in;

  will restore the screen content even if the height of the window changed (if the width changed, more manipulation is needed).

## Control of the process list

With the exception of Title_set(), all these calls require that PM is running, they would not work under alternative Session Managers.

`process_entry()`

  returns a list of the following data:

  Title of the process (in the `Ctrl-Esc` list);

  window handle of switch entry of the process (in the `Ctrl-Esc` list);

  window handle of the icon of the process;

  process handle of the owner of the entry in `Ctrl-Esc` list;

  process id of the owner of the entry in `Ctrl-Esc` list;

  session id of the owner of the entry in `Ctrl-Esc` list;

  whether visible in `Ctrl-Esc` list;

  whether item cannot be switched to (note that it is not actually grayed in the `Ctrl-Esc` list));

  whether participates in jump sequence;

  program type. Possible values are:

           PROG_DEFAULT                       0
           PROG_FULLSCREEN                    1
           PROG_WINDOWABLEVIO                 2
           PROG_PM                            3
           PROG_VDM                           4
           PROG_WINDOWEDVDM                   7

  Although there are several other program types for WIN-OS/2 programs, these do not show up in this field. Instead, the PROG_VDM or PROG_WINDOWEDVDM program types are used. For instance, for PROG_31_STDSEAMLESSVDM, PROG_WINDOWEDVDM is used. This is because all the WIN-OS/2 programs run in DOS sessions. For example, if a program is a windowed WIN-OS/2 program, it runs in a PROG_WINDOWEDVDM session. Likewise, if it's a full-screen WIN-OS/2 program, it runs in a PROG_VDM session.

  switch-entry handle.

Optional arguments: the pid and the window-handle of the application running in the OS/2 session to query.

`process_hentry()`

  similar to process_entry(), but returns a hash reference, the keys being

        title owner_hwnd icon_hwnd owner_phandle owner_pid owner_sid
        visible nonswitchable jumpable ptype sw_entry

  (a copy of the list of keys is in @hentry_fields).

`process_entries()`

  similar to process_entry(), but returns a list of array reference for all the elements in the switch list (one controlling `Ctrl-Esc` window).

`process_hentries()`

  similar to process_hentry(), but returns a list of hash reference for all the elements in the switch list (one controlling `Ctrl-Esc` window).

`change_entry()`

  changes a process entry, arguments are the same as `process_entry()` returns.

`change_entryh()`

  Similar to change_entry(), but takes a hash reference as an argument.

`process_hwnd()`

  returns the `owner_hwnd` of the process entry (for VIO windowed processes this is the frame window of the session).

`Title()`

  returns the text of the task switch menu entry of the current session. (There is no way to get this info in non-standard Session Managers. This implementation is a shortcut via `process_entry().)`

`Title_set(newtitle)`

  tries two different interfaces. The Session Manager one does not work with some windows (if the title is set from the start). This is a limitation of OS/2, in such a case $^E is set to 372 (type

        help 372

  for a funny - and wrong - explanation ;-). In such cases a direct-manipulation of low-level entries is used (same as bothTitle_set()). Keep in mind that some versions of OS/2 leak memory with such a manipulation.

`winTitle()`

  returns text of the titlebar of the current process' window.

`winTitle_set(newtitle)`

  sets text of the titlebar of the current process' window. The change does not affect the text of the switch entry of the current window.

`swTitle_set(newtitle)`

  sets text of the task switch menu entry of the current process' window. [There is no API to query this title.] Does it via SwitchEntry interface, not Session manager interface. The change does not affect the text of the titlebar of the current window.

`bothTitle_set(newtitle)`

  sets text of the titlebar and task switch menu of the current process' window via direct manipulation of the windows' texts.

`SwitchToProgram([$sw_entry])`

  switch to session given by a switch list handle (defaults to the entry of our process).

  Use of this function causes another window (and its related windows) of a PM session to appear on the front of the screen, or a switch to another session in the case of a non-PM program. In either case, the keyboard (and mouse for the non-PM case) input is directed to the new program.

## Control of the PM windows

Some of these API's require sending a message to the specified window. In such a case the process needs to be a PM process, or to be morphed to a PM process via OS2::MorphPM().

For a temporary morphing to PM use OS2::localMorphPM class.

Keep in mind that PM windows are engaged in 2 ``orthogonal'' window trees, as well as in the z-order list.

One tree is given by the parent/child relationship. This relationship affects drawing (child is drawn relative to its parent (lower-left corner), and the drawing is clipped by the parent's boundary; parent may request that it's drawing is clipped to be confined to the outsize of the childs and/or siblings' windows); hiding; minimizing/restoring; and destroying windows.

Another tree (not necessarily connected?) is given by ownership relationship. Ownership relationship assumes cooperation of the engaged windows via passing messages on ``important events''; e.g., scrollbars send information messages when the ``bar'' is moved, menus send messages when an item is selected; frames move/hide/unhide/minimize/restore/change-z-order-of owned frames when the owner is moved/etc., and destroy the owned frames (even when these frames are not descendants) when the owner is destroyed; etc. [An important restriction on ownership is that owner should be created by the same thread as the owned thread, so they engage in the same message queue.]

Windows may be in many different state: Focused (take keyboard events) or not, Activated (=Frame windows in the parent/child tree between the root and the window with the focus; usually indicate such ``active state'' by titlebar highlights, and take mouse events) or not, Enabled/Disabled (this influences the ability to update the graphic, and may change appearance, as for enabled/disabled buttons), Visible/Hidden, Minimized/Maximized/Restored, Modal or not, etc.

The APIs below all `die()` on error with the message being $^E.

`WindowText($hwnd)`

  gets ``a text content'' of a window. Requires (morphing to) PM.

`WindowText_set($hwnd, $text)`

  sets ``a text content'' of a window. Requires (morphing to) PM.

`($x, $y, $flags, $width, $height, $behind, @rest) = WindowPos($hwnd)`

  gets window position info as 8 integers (of `SWP`), in the order suitable for WindowPos_set(). @rest is marked as ``reserved'' in PM docs. $flags is a combination of `SWP_*` constants.

`$hash = hWindowPos($hwnd)`

  gets window position info as a hash reference; the keys are `flags width height x y behind hwnd reserved1 reserved2`.

  Example:

        exit unless $hash->{flags} & SWP_MAXIMIZE;    # Maximized

`WindowPos_set($hwnd, $x, $y, $flags = SWP_MOVE, $width = 0, $height = 0, $behind = HWND_TOP)`

  Set state of the window: position, size, zorder, show/hide, activation, minimize/maximize/restore etc. Which of these operations to perform is governed by $flags.

`hWindowPos_set($hash, [$hwnd])`

  Same as `WindowPos_set`, but takes the position from keys `fl width height x y behind hwnd` of the hash referenced by $hash. If $hwnd is explicitly specified, it overrides `$hash-`{hwnd}>. If $hash->{flags} is not specified, it is calculated basing on the existing keys of $hash. Requires (morphing to) PM.

  Example:

        hWindowPos_set {flags => SWP_MAXIMIZE}, $hwnd; # Maximize

`($pid, $tid) = WindowProcess($hwnd)`

  gets PID and TID of the process associated to the window.

`ClassName($hwnd)`

  returns the class name of the window.

  If this window is of any of the preregistered WC_* classes the class name returned is in the form ``#nnnnn'', where ``nnnnn'' is a group of up to five digits that corresponds to the value of the WC_* class name constant.

`FocusWindow()`

  returns the handle of the focus window. Optional argument for specifying the desktop to use.

`FocusWindow_set($hwnd)`

  set the focus window by handle. Optional argument for specifying the desktop to use. E.g, the first entry in `program_entries()` is the `Ctrl-Esc` list. To show an application, use either one of

             WinShowWindow( $hwnd, 1 );
             FocusWindow_set( $hwnd );
             SwitchToProgram($switch_handle);

  (Which work with alternative focus-to-front policies?) Requires (morphing to) PM.

  Switching focus to currently-unfocused window moves the window to the front in Z-order; use `FocusWindow_set_keep_Zorder()` to avoid this.

`FocusWindow_set_keep_Zorder($hwnd)`

  same as FocusWindow_set(), but preserves the Z-order of windows.

`ActiveWindow([$parentHwnd])`

  gets the active subwindow's handle for $parentHwnd or desktop. Returns FALSE if none.

`ActiveWindow_set($hwnd, [$parentHwnd])`

  sets the active subwindow's handle for $parentHwnd or desktop. Requires (morphing to) PM.

`ShowWindow($hwnd [, $show])`

  Set visible/hidden flag of the window. Default: $show is TRUE.

`EnableWindowUpdate($hwnd [, $update])`

  Set window visibility state flag for the window for subsequent drawing. No actual drawing is done at this moment. Use `ShowWindow($hwnd, $state)` when redrawing is needed. While update is disabled, changes to the ``window state'' do not change the appearance of the window. Default: $update is TRUE.

  (What is manipulated is the bit `WS_VISIBLE` of the window style.)

`EnableWindow($hwnd [, $enable])`

  Set the window enabled state. Default: $enable is TRUE.

  Results in `WM_ENABLED` message sent to the window. Typically, this would change the appearence of the window. If at the moment of disabling focus is in the window (or a descendant), focus is lost (no focus anywhere). If focus is needed, it can be reassigned explicitly later.

IsWindowEnabled(), IsWindowVisible(), `IsWindowShowing()`

  these functions take $hwnd as an argument. `IsWindowEnabled()` queries the state changed by EnableWindow(), `IsWindowVisible()` the state changed by ShowWindow(), `IsWindowShowing()` is true if there is a part of the window visible on the screen.

`PostMsg($hwnd, $msg, $mp1, $mp2)`

  post message to a window. The meaning of $mp1, $mp2 is specific for each message id $msg, they default to 0. E.g.,

        use OS2::Process qw(:DEFAULT WM_SYSCOMMAND WM_CONTEXTMENU
                            WM_SAVEAPPLICATION WM_QUIT WM_CLOSE
                            SC_MAXIMIZE SC_RESTORE);
        $hwnd = process_hentry()->{owner_hwnd};
        # Emulate choosing `Restore' from the window menu:
        PostMsg $hwnd, WM_SYSCOMMAND, MPFROMSHORT(SC_RESTORE); # Not immediate

        # Emulate `Show-Contextmenu' (Double-Click-2), two ways:
        PostMsg ActiveWindow, WM_CONTEXTMENU;
        PostMsg FocusWindow, WM_CONTEXTMENU;

        /* Emulate `Close' */
        PostMsg ActiveWindow, WM_CLOSE;

        /* Same but with some "warnings" to the application */
        $hwnd = ActiveWindow;
        PostMsg $hwnd, WM_SAVEAPPLICATION;
        PostMsg $hwnd, WM_CLOSE;
        PostMsg $hwnd, WM_QUIT;

  In fact, `MPFROMSHORT()` may be omitted above.

  For messages to other processes, messages which take/return a pointer are not supported.

`MP*()`

  The functions MPFROMSHORT(), MPVOID(), MPFROMCHAR(), MPFROM2SHORT(), MPFROMSH2CH(), `MPFROMLONG()` can be used the same way as from C. Use them to construct parameters $m1, $m2 to PostMsg().

  These functions are not exported by default.

`$eh = BeginEnumWindows($hwnd)`

  starts enumerating immediate child windows of $hwnd in z-order. The enumeration reflects the state at the moment of `BeginEnumWindows()` calls; use `IsWindow()` to be sure. All the functions in this group require (morphing to) PM.

`$kid_hwnd = GetNextWindow($eh)`

  gets the next kid in the list. Gets 0 on error or when the list ends.

`EndEnumWindows($eh)`

  End enumeration and release the list.

`@list = ChildWindows([$hwnd])`

  returns the list of child windows at the moment of the call. Same remark as for enumeration interface applies. Defaults to HWND_DESKTOP. Example of usage:

        sub l {
          my ($o,$h) = @_;
          printf ' ' x $o . "%#x\n", $h;
          l($o+2,$_) for ChildWindows $h;
        }
        l 0, $HWND_DESKTOP

`IsWindow($hwnd)`

  true if the window handle is still valid.

`QueryWindow($hwnd, $type)`

  gets the handle of a related window. $type should be one of `QW_*` constants.

`IsChild($hwnd, $parent)`

  return TRUE if $hwnd is a descendant of $parent.

`WindowFromId($hwnd, $id)`

  return a window handle of a child of $hwnd with the given $id.

        hwndSysMenu = WinWindowFromID(hwndDlg, FID_SYSMENU);
        WinSendMsg(hwndSysMenu, MM_SETITEMATTR,
            MPFROM2SHORT(SC_CLOSE, TRUE),
            MPFROM2SHORT(MIA_DISABLED, MIA_DISABLED));

`WindowFromPoint($x, $y [, $hwndParent [, $descedantsToo]])`

  gets a handle of a child of $hwndParent at `($x,$y)`. If $descedantsToo (defaulting to 1) then children of children may be returned too. May return $hwndParent (defaults to desktop) if no suitable children are found, or 0 if the point is outside the parent.

  $x and $y are relative to $hwndParent.

`EnumDlgItem($dlgHwnd, $type [, $relativeHwnd])`

  gets a dialog item window handle for an item of type $type of $dlgHwnd relative to $relativeHwnd, which is descendant of $dlgHwnd. $relativeHwnd may be specified if $type is EDI_FIRSTTABITEM or EDI_LASTTABITEM.

  The return is always an immediate child of hwndDlg, even if hwnd is not an immediate child window. $type may be

EDI_FIRSTGROUPITEM

  First item in the same group.

EDI_FIRSTTABITEM

  First item in dialog with style WS_TABSTOP. hwnd is ignored.

EDI_LASTGROUPITEM

  Last item in the same group.

EDI_LASTTABITEM

  Last item in dialog with style WS_TABSTOP. hwnd is ignored.

EDI_NEXTGROUPITEM

  Next item in the same group. Wraps around to beginning of group when the end of the group is reached.

EDI_NEXTTABITEM

  Next item with style WS_TABSTOP. Wraps around to beginning of dialog item list when end is reached.

EDI_PREVGROUPITEM

  Previous item in the same group. Wraps around to end of group when the start of the group is reached. For information on the WS_GROUP style, see Window Styles.

EDI_PREVTABITEM

  Previous item with style WS_TABSTOP. Wraps around to end of dialog item list when beginning is reached.

`DesktopWindow()`

  gets the actual window handle of the PM desktop; most APIs accept the pseudo-handle `HWND_DESKTOP` instead. Keep in mind that the WPS desktop (one with `WindowText()` being `"Desktop"`) is a different beast?!

`TopLevel($hwnd)`

  gets the toplevel window of $hwnd.

`ResetWinError()`

  Resets $^E. One may need to call it before the `Win*`-class APIs which may return 0 during normal operation. In such a case one should check both for return value being zero and $^E being non-zero. The following APIs do `ResetWinError()` themselves, thus do not need an explicit one:

        WindowPtr
        WindowULong
        WindowUShort
        WindowTextLength
        ActiveWindow
        PostMsg

  This function is normally not needed. Not exported by default.

## Control of the PM data

`ActiveDesktopPathname()`

  gets the path of the directory which corresponds to Desktop.

`ClipbrdText()`

  gets the content of the clipboard. An optional argument is the format of the data in the clipboard (defaults to `CF_TEXT`).

  Note that the usual convention is to have clipboard data with `"\r\n"` as line separators.

`ClipbrdText_set($txt)`

  sets the text content of the clipboard. Unless the optional argument is TRUE, will convert newlines to `"\r\n"`. Another optional argument is the format of the data in the clipboard (defaults to `CF_TEXT`).

InvalidateRect
CreateFrameControl
ClipbrdFmtInfo
ClipbrdOwner
ClipbrdViewer
ClipbrdData
OpenClipbrd
CloseClipbrd
ClipbrdData_set
ClipbrdOwner_set
ClipbrdViewer_set
EnumClipbrdFmts
EmptyClipbrd
AddAtom
FindAtom
DeleteAtom
AtomUsage
AtomName
AtomLength
SystemAtomTable
CreateAtomTable
DestroyAtomTable

  Low-level methods to access clipboard and the atom table(s).

# OS2::localMorphPM class

This class morphs the process to PM for the duration of the given scope.

      {
        my $h = OS2::localMorphPM->new(0);
        # Do something
      }

The argument has the same meaning as one to OS2::MorphPM(). Calls can nest with internal ones being NOPs.

# TODO

Add tests for:

            SwitchToProgram
            ClassName
            out_codepage
            out_codepage_set
            in_codepage
            in_codepage_set
            cursor
            cursor_set
            screen
            screen_set
            process_codepages
            QueryWindow
            EnumDlgItem
            WindowPtr
            WindowULong
            WindowUShort
            SetWindowBits
            SetWindowPtr
            SetWindowULong
            SetWindowUShort
            my_type
            file_type
            scrsize
            scrsize_set

Document and test: Query/SetWindowULong/Short/Ptr, SetWindowBits. InvalidateRect, CreateFrameControl, ClipbrdFmtInfo ClipbrdOwner ClipbrdViewer ClipbrdData OpenClipbrd CloseClipbrd ClipbrdData_set ClipbrdOwner_set ClipbrdViewer_set EnumClipbrdFmts EmptyClipbrd AddAtom FindAtom DeleteAtom AtomUsage AtomName AtomLength SystemAtomTable CreateAtomTable DestroyAtomTable

Implement SOMETHINGFROMMR.

      >But I wish to change the default button if the user enters some
      >text into an entryfield.  I can detect the entry ok, but can't
      >seem to get the button to change to default.
      >
      >No matter what message I send it, it's being ignored.

      You need to get the style of the buttons using WinQueryWindowULong/QWL_STYLE,
      set and reset the BS_DEFAULT bits as appropriate and then use
      WinSetWindowULong/QWL_STYLE to set the button style.
      Something like this:
        hwnd1 = WinWindowFromID (hwnd, id1);
        hwnd2 = WinWindowFromID (hwnd, id2);
        style1 = WinQueryWindowULong (hwnd1, QWL_STYLE);
        style2 = WinQueryWindowULong (hwnd2, QWL_STYLE);
        style1 |= style2 & BS_DEFAULT;
        style2 &= ~BS_DEFAULT;
        WinSetWindowULong (hwnd1, QWL_STYLE, style1);
        WinSetWindowULong (hwnd2, QWL_STYLE, style2);

     > How to do query and change a frame creation flags for existing window?

     Set the style bits that correspond to the FCF_* flag for the frame
     window and then send a WM_UPDATEFRAME message with the appropriate FCF_*
     flag in mp1.

     ULONG ulFrameStyle;
     ulFrameStyle = WinQueryWindowULong( WinQueryWindow(hwnd, QW_PARENT),
     QWL_STYLE );
     ulFrameStyle = (ulFrameStyle & ~FS_SIZEBORDER) | FS_BORDER;
     WinSetWindowULong(   WinQueryWindow(hwnd, QW_PARENT),
                          QWL_STYLE,
                          ulFrameStyle );
     WinSendMsg( WinQueryWindow(hwnd, QW_PARENT),
                 WM_UPDATEFRAME,
                 MPFROMP(FCF_SIZEBORDER),
                 MPVOID );

     If the FCF_* flags you want to change does not have a corresponding FS_*
     style (i.e. the FCF_* flag corresponds to the presence/lack of a frame
     control rather than a property of the frame itself) then you create or
     destroy the appropriate control window using the correct FID_* window
     identifier and then send the WM_UPDATEFRAME message with the appropriate
     FCF_* flag in mp1.

     /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -*
      |  SetFrameBorder()                                                          |
      |    Changes a frame window's border to the requested type.                  |
      |                                                                            |
      |  Parameters on entry:                                                      |
      |    hwndFrame     -> Frame window whose border is to be changed.            |
      |    ulBorderStyle -> Type of border to change to.                           |
      |                                                                            |
      |  Returns:                                                                  |
      |    BOOL          -> Success indicator.                                     |
      |                                                                            |
      * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -*/
     BOOL SetFrameBorder( HWND hwndFrame, ULONG ulBorderType )  {
       ULONG  ulFrameStyle;
       BOOL   fSuccess = TRUE;

       ulFrameStyle = WinQueryWindowULong( hwndFrame, QWL_STYLE );

       switch ( ulBorderType )  {
         case FS_SIZEBORDER :
           ulFrameStyle = (ulFrameStyle & ~(FS_DLGBORDER | FS_BORDER))
                          | FS_SIZEBORDER;
           break;

         case FS_DLGBORDER :
           ulFrameStyle = (ulFrameStyle & ~(FS_SIZEBORDER | FS_BORDER))
                          | FS_DLGBORDER;
           break;

         case FS_BORDER :
           ulFrameStyle = (ulFrameStyle & ~(FS_SIZEBORDER | FS_DLGBORDER))
                          | FS_BORDER;
           break;

         default :
           fSuccess = FALSE;
           break;
       }  // end switch

       if ( fSuccess )  {
         fSuccess = WinSetWindowULong( hwndFrame, QWL_STYLE, ulFrameStyle );

         if ( fSuccess )  {
           fSuccess = (BOOL)WinSendMsg( hwndFrame, WM_UPDATEFRAME, 0, 0 );
           if ( fSuccess )
             fSuccess = WinInvalidateRect( hwndFrame, NULL, TRUE );
         }
       }

       return ( fSuccess );

     }  // End SetFrameBorder()

             hwndMenu=WinLoadMenu(hwndParent,NULL,WND_IMAGE);
             WinSetWindowUShort(hwndMenu,QWS_ID,FID_MENU);
             ulStyle=WinQueryWindowULong(hwndMenu,QWL_STYLE);
             WinSetWindowULong(hwndMenu,QWL_STYLE,ulStyle|MS_ACTIONBAR);
             WinSendMsg(hwndParent,WM_UPDATEFRAME,MPFROMSHORT(FCF_MENU),0L);

      OS/2-windows have another "parent" called the *owner*,
      which must be set separately - to get a close relationship:

        WinSetOwner (hwndFrameChild, hwndFrameMain);

      Now your child should move with your main window!
      And always stays on top of it....

      To avoid this, for example for dialogwindows, you can
      also "disconnect" this relationship with:

        WinSetWindowBits (hwndFrameChild, QWL_STYLE
                          , FS_NOMOVEWITHOWNER
                          , FS_NOMOVEWITHOWNER);

     Adding a button icon later:

     /* switch the button style to BS_MINIICON */
     WinSetWindowBits(hwndBtn, QWL_STYLE, BS_MINIICON, BS_MINIICON) ;

     /* set up button control data */
     BTNCDATA    bcd;
     bcd.cb = sizeof(BTNCDATA);
     bcd.hImage = WinLoadPointer(HWND_DESKTOP, dllHandle, ID_ICON_BUTTON1) ;
     bcd.fsCheckState = bcd.fsHiliteState = 0 ;

     WNDPARAMS   wp;
     wp.fsStatus = WPM_CTLDATA;
     wp.pCtlData = &bcd;

     /* add the icon on the button */
     WinSendMsg(hwndBtn, WM_SETWINDOWPARAMS, (MPARAM)&wp, NULL);

     MO> Can anyone tell what OS/2 expects of an application to be properly
     MO> minimized to the desktop?
     case WM MINMAXFRAME :
     {
       BOOL  fShow = ! (((PSWP) mp1)->fl & SWP MINIMIZE);
       HENUM henum;

       HWND  hwndChild;

       WinEnableWindowUpdate ( hwnd, FALSE );

       for (henum=WinBeginEnumWindows(hwnd);
            (hwndChild = WinGetNextWindow (henum)) != 0; )
       WinShowWindow ( hwndChild, fShow );

       WinEndEnumWindows ( henum );
       WinEnableWindowUpdate ( hwnd, TRUE );
     }
     break;

Why `hWindowPos DesktopWindow` gives `behind => HWND_TOP`?

# $^E

the majority of the APIs of this module set $^E on failure (no matter whether they `die()` on failure or not). By the semantic of PM API which returns something other than a boolean, it is impossible to distinguish failure from a ``normal'' 0-return. In such cases `$^E == 0` indicates an absence of error.

# EXPORTS

In addition to symbols described above, the following constants (available also via module `OS2::Process::Const`) are exportable. Note that these symbols live in package `OS2::Process::Const`, they are not available by full name through `OS2::Process`!

      HWND_*                Standard (abstract) window handles
      WM_*                  Message ids
      SC_*                  WM_SYSCOMMAND flavor
      SWP_*                 Size/move etc flag
      WC_*                  Standard window classes
      PROG_*                Program category (PM, VIO etc)
      QW_*                  Query-Window flag
      EDI_*                 Enumerate-Dialog-Item code
      WS_*                  Window Style flag
      QWS_*                 Query-window-UShort offsets
      QWP_*                 Query-window-pointer offsets
      QWL_*                 Query-window-ULong offsets
      FF_*                  Frame-window state flags
      FI_*                  Frame-window information flags
      LS_*                  List box styles
      FS_*                  Frame style
      FCF_*                 Frame creation flags
      BS_*                  Button style
      MS_*                  Menu style
      TBM_*                 Title bar messages?
      CF_*                  Clipboard formats
      CFI_*                 Clipboard storage type
      FID_*                 ids of subwindows of frames

# BUGS

whether a given API dies or returns FALSE/empty-list on error may be confusing. This may change in the future.

# AUTHOR

Andreas Kaiser <ak@ananke.s.bawue.de>, Ilya Zakharevich <ilya@math.ohio-state.edu>.

# SEE ALSO

`spawn*`() system calls, the OS2::Proc manpage and the OS2::WinObject manpage modules.

OS2::Process - exports constants for system call, and process control on OS2.