Conference bulova::decw_jan-89_to_nov-90

978.0. "XSET_TRANSIENT_FOR crashes window manager !" by STKHLM::SUNDSTROM () Tue Jun 20 1989 02:55

	A customer has observed that under certain circumbstances the
	window manager will die (under VMS with ACCESS VIOLATION, under
	ULTRIX with bus error).

	An investigation showed that a number of popup-windows were 
	'managed' (he uses UIL) before the main window was reallized.
	There is a hint in the documentation that the main window should
	be realized before any popup window which I told him and he was
	satisfied.

	The real problem is that if a window that has the WM_TRANSIENT_FOR
	hint set is mapped before the window that its property points to is
	mapped, the window manager will crash.

	Included is a small example written in Xlib that will crash the DEC
	window manager. (The MIT window manager will not crash but on the
	other hand it does not care about WM_TRANSIENT_FOR it seems..)

	I wonder if this in a known problem and if there is any fix for it.
	Even if the obvious workaround is not to do what I just described
	many inexperienced programmers will not see our software as 'robust'.

	Regards,

			/Per Sundstr�m @ Country Support Sweden.

-------------------
	The program:

#include <X11/Xlib.h>

    Display * disp;
    Screen * screen;
    Window rwin, win1, win2;
    unsigned long black, white;

    main () {

    disp = XOpenDisplay ("");
    screen = XDefaultScreenOfDisplay (disp);
    rwin = XDefaultRootWindow (disp);
    black = XBlackPixelOfScreen (screen);
    white = XWhitePixelOfScreen (screen);

                                                                                    win1 = XCreateSi
    win2 = XCreateSimpleWindow (disp, rwin, 160, 50, 100, 100, 1, black, white)
;
    XSetTransientForHint(disp,win2,win1);
    XMapWindow (disp, win2);
    XMapWindow (disp, win1);
    XSync(disp,0);

        while(1){}
    }

    This is a known bug and the fix will be in the
    next major release of VMS DECwindows.  
    

Thank you, I hope that goes for ULTRIX as well !

			/Per.

    If you want to make absolutely sure it's fixed in the
    next version of ULTRIX, please submit a report to the
    appropriate bug-report data base.
    
    John