Improved support for faulty X11 clients (STR #2385)

git-svn-id: file:///fltk/svn/fltk/branches/branch-1.3@7866 ea41ed52-d2ee-0310-a9c1-e6b18d33e121

CHANGES

@@ -1,5 +1,6 @@
 CHANGES IN FLTK 1.3.0
 
+	- Improved support for faulty X11 clients (STR #2385)
 	- Fixed xclass support for Fl_Window (STR #2053)
 	- Fixed Caps Lock handling in X11/XIM (STR #2366)
 	- Fixed handling of missing fonts in Xft (STR #2355)

src/Fl_x.cxx

@@ -804,6 +804,27 @@ static Fl_Window* resize_bug_fix;
 static char unknown[] = "<unknown>";
 const int unknown_len = 10;
 
+extern "C" {
+
+static int xerror = 0;
+
+static int ignoreXEvents(Display *display, XErrorEvent *event) {
+  xerror = 1;
+  return 0;
+}
+
+static XErrorHandler catchXExceptions() {
+  xerror = 0;
+  return ignoreXEvents;
+}
+
+static int wasXExceptionRaised() {
+  return xerror;
+}
+
+}
+
+
 int fl_handle(const XEvent& thisevent)
 {
   XEvent xevent = thisevent;
@@ -1360,16 +1381,22 @@ int fl_handle(const XEvent& thisevent)
     int xpos, ypos;
     Window junk;
     
+    // on some systems, the ReparentNotify event is not handled as we would expect.
+    XErrorHandler oldHandler = XSetErrorHandler(catchXExceptions());
+
     //ReparentNotify gives the new position of the window relative to
     //the new parent. FLTK cares about the position on the root window.
     XTranslateCoordinates(fl_display, xevent.xreparent.parent,
                           XRootWindow(fl_display, fl_screen),
                           xevent.xreparent.x, xevent.xreparent.y,
                           &xpos, &ypos, &junk);
+    XSetErrorHandler(oldHandler);
 
     // tell Fl_Window about it and set flag to prevent echoing:
+    if ( !wasXExceptionRaised() ) {
       resize_bug_fix = window;
       window->position(xpos, ypos);
+    }
     break;
     }
   }