diff --git a/rfb_win32/WMShatter.cxx b/rfb_win32/WMShatter.cxx
new file mode 100644
index 0000000..f6a7484
--- /dev/null
+++ b/rfb_win32/WMShatter.cxx
@@ -0,0 +1,57 @@
+/* Copyright (C) 2002-2003 RealVNC Ltd.  All Rights Reserved.
+ *    
+ * This is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ * 
+ * This software is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this software; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307,
+ * USA.
+ */
+
+// -=- WMShatter.cxx
+
+#include <rfb_win32/WMShatter.h>
+
+#include <rfb/LogWriter.h>
+
+using namespace rfb;
+using namespace rfb::win32;
+
+static LogWriter vlog("WMShatter");
+
+bool
+rfb::win32::IsSafeWM(HWND window, UINT msg, WPARAM wParam, LPARAM lParam) {
+  bool result = true;
+  switch (msg) {
+    // - UNSAFE MESSAGES
+  case WM_TIMER:
+    result = lParam == 0;
+    break;
+  };
+  if (!result) {
+    vlog.info("IsSafeWM: 0x%x received 0x%x(%u, %lu) - not safe", window, msg, wParam, lParam);
+  }
+  return result;
+}
+
+LRESULT
+rfb::win32::SafeDefWindowProc(HWND window, UINT msg, WPARAM wParam, LPARAM lParam) {
+  if (IsSafeWM(window, msg, wParam, lParam))
+    return DefWindowProc(window, msg, wParam, lParam);
+  return 0;
+}
+
+LRESULT
+rfb::win32::SafeDispatchMessage(const MSG* msg) {
+  if (IsSafeWM(msg->hwnd, msg->message, msg->wParam, msg->lParam))
+    return DispatchMessage(msg);
+  return 0;
+}