yuki@flab.fujitsu.co.jp (Hiroyuki YOSHIDA) (06/01/90)
We coded a parent killer such as:
/* ARGSUSED */
static void parentKiller(w,client_data,call_data)
Widget w;
caddr_t client_data; /* UNUSED */
caddr_t call_data; /* UNUSED */
{
Widget papa = XtParent(w);
int brothers = ((CompositeWidget)papa)->composite.num_children;
if( brothers == 0 )
XtDestroyWidget(papa);
}
Then, attached the killer for widgets in a widgets tree using:
XtAddCallback(w,XtNdestroyCallback,parentKiller,(caddr_t)NULL);
This successfully worked before we patched fix-10 & -11.
After fix-10/11, a server error occurs and the program exits. The
error message is:
X Error of failed request: BadWindow (invalid Window parameter)
Major opcode of failed request: 4 (X_DestroyWindow)
Minor opcode of failed request: 0
Resource id in failed request: 0xb0039d
Serial number of failed request: 4073
Current serial number in output stream: 4198
The resource id (0xb0039d) designates the child's window.
We can avoid the error using work-proc technique, such as:
/* ARGSUSED */
static void parentKiller(w,client_data,call_data)
Widget w;
caddr_t client_data; /* UNUSED */
caddr_t call_data; /* UNUSED */
{
Widget papa = XtParent(w);
int brothers = ((CompositeWidget)papa)->composite.num_children;
if( brothers == 0 )
(void)XtAppAddWorkProc(app,XtDestroyWidget,(caddr_t)papa);
/* Killing parent is postponed. */
}
In addition, we can avoid the error by not applying a part of fix-10:
*** /tmp/,RCSt1a03963 Thu Apr 19 19:44:53 1990
--- mit/lib/Xt/Destroy.c Thu Apr 19 19:44:55 1990
***************
*** 155,162 ****
Recursive(widget, Phase2Destroy);
app->in_phase2_destroy = outerInPhase2Destroy;
! /* popups destroy their own window if parent->being_destroyed */
! if (window != NULL && (parent == NULL || !parent->core.being_destroyed))
XDestroyWindow(display, window);
} /* XtPhase2Destroy */
--- 165,171 ----
Recursive(widget, Phase2Destroy);
app->in_phase2_destroy = outerInPhase2Destroy;
! if (window)
XDestroyWindow(display, window);
} /* XtPhase2Destroy */
The problem may occur when the child's window is doubly destroyed in a
very short time.
Where is the BUG? In fix-10, server program, or our usage?
--
Hiroyuki Yoshida
yuki@flab.fujitsu.co.jp
yuki%flab.fujitsu.co.jp@uunet.uu.NET