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From: dex@hpcvlx.cv.hp.com (Dex Smith)
Newsgroups: comp.windows.x
Subject: Re: WM_DELETE and the Shell Widget
Message-ID: <100920264@hpcvlx.cv.hp.com>
Date: 19 Dec 90 16:26:39 GMT
References: <224@ebt-inc.UUCP>
Organization: Hewlett-Packard Co., Corvallis, OR, USA
Lines: 38


In Motif, the VendorShell widget class (which is used by application
shells) defines an XmNdeleteResponse resource.  The default value for this
resource is XmDESTORY.  So, when the window receives a WM_DELETE_WINDOW 
message (ie. window manager Close command), the shell is destroyed.  If it
is the application's top-level shell, the process terminates.

To "trap" the window manager Close command, you do two things:

 1. Set the top-level shell's "deleteResponse" resource to XmDO_NOTHING:

        ac = 0;
        XtSetArg (al[ac], XmNdeletResponse, XmDO_NOTHING);  ac++;
        XtSetValues (toplevel, al, ac);

 2. Add a window manager protocol callback to detect when the shell gets
    the WM_DELETE_WINDOW message:

        Atom  XaWmDelete;

        XaWmDelete= XInternAtom(XtDisplay(toplevel), "WM_DELETE_WINDOW", False);
        XmAddWMProtocolCallback(toplevel, XaWmDelete, MenuCB, MENU_File_Exit);

    This example code sets the callback to call a MenuCB() callback routine
    with an application-specific defined client_data of MENU_File_Exit.  
    Presumably, this is the same callback and client_data used for the
    Exit command in the application's File menu.  (That is, the window 
    manager's Close command is now equivalent to the Exit command in the 
    File menu.)

I hope this helps!

- Dex Smith, Learning Products Developer
  Interface Technology Operation
  Hewlett-Packard Company
  Corvallis, Oregon

  dex@hpcvlx.cv.hp.com