diff --git a/widget/gtk2/nsGtkKeyUtils.cpp b/widget/gtk2/nsGtkKeyUtils.cpp
index 5c9fd7f911db..359812a34d7c 100644
--- a/widget/gtk2/nsGtkKeyUtils.cpp
+++ b/widget/gtk2/nsGtkKeyUtils.cpp
@@ -22,6 +22,7 @@
  * the Initial Developer. All Rights Reserved.
  *
  * Contributor(s):
+ *   Masayuki Nakano <masayuki@d-toybox.com>
  *
  * Alternatively, the contents of this file may be used under the terms of
  * either the GNU General Public License Version 2 or later (the "GPL"), or
@@ -37,6 +38,10 @@
  *
  * ***** END LICENSE BLOCK ***** */
 
+#include "prlog.h"
+
+#include "nsGtkKeyUtils.h"
+
 #include <gdk/gdkkeysyms.h>
 #ifndef GDK_Sleep
 #define GDK_Sleep 0x1008ff2f
@@ -49,6 +54,10 @@
 #include "nsGUIEvent.h"
 #include "keysym2ucs.h"
 
+#ifdef PR_LOGGING
+PRLogModuleInfo* gKeymapWrapperLog = nsnull;
+#endif // PR_LOGGING
+
 #include "mozilla/Util.h"
 
 using namespace mozilla;
@@ -328,3 +337,79 @@ PRUint32 nsConvertCharCodeToUnicode(GdkEventKey* aEvent)
     // I guess we couldn't convert
     return 0;
 }
+
+namespace mozilla {
+namespace widget {
+
+#define MOZ_MODIFIER_KEYS "MozKeymapWrapper"
+
+KeymapWrapper* KeymapWrapper::sInstance = nsnull;
+
+/* static */ KeymapWrapper*
+KeymapWrapper::GetInstance()
+{
+    if (sInstance) {
+        return sInstance;
+    }
+
+    sInstance = new KeymapWrapper();
+    return sInstance;
+}
+
+KeymapWrapper::KeymapWrapper() :
+    mInitialized(false), mGdkKeymap(gdk_keymap_get_default())
+{
+#ifdef PR_LOGGING
+    if (!gKeymapWrapperLog) {
+        gKeymapWrapperLog = PR_NewLogModule("KeymapWrapperWidgets");
+    }
+    PR_LOG(gKeymapWrapperLog, PR_LOG_ALWAYS,
+        ("KeymapWrapper(%p): Constructor, mGdkKeymap=%p",
+         this, mGdkKeymap));
+#endif // PR_LOGGING
+
+    g_signal_connect(mGdkKeymap, "keys-changed",
+                     (GCallback)OnKeysChanged, this);
+
+    // This is necessary for catching the destroying timing.
+    g_object_weak_ref(G_OBJECT(mGdkKeymap),
+                      (GWeakNotify)OnDestroyKeymap, this);
+}
+
+KeymapWrapper::~KeymapWrapper()
+{
+    PR_LOG(gKeymapWrapperLog, PR_LOG_ALWAYS,
+        ("KeymapWrapper(%p): Destructor", this));
+}
+
+/* static */ void
+KeymapWrapper::OnDestroyKeymap(KeymapWrapper* aKeymapWrapper,
+                               GdkKeymap *aGdkKeymap)
+{
+    PR_LOG(gKeymapWrapperLog, PR_LOG_ALWAYS,
+        ("KeymapWrapper: OnDestroyKeymap, aGdkKeymap=%p, aKeymapWrapper=%p",
+         aGdkKeymap, aKeymapWrapper));
+    MOZ_ASSERT(aKeymapWrapper == sInstance,
+               "Desroying unexpected instance");
+    delete sInstance;
+    sInstance = nsnull;
+}
+
+/* static */ void
+KeymapWrapper::OnKeysChanged(GdkKeymap *aGdkKeymap,
+                             KeymapWrapper* aKeymapWrapper)
+{
+    PR_LOG(gKeymapWrapperLog, PR_LOG_ALWAYS,
+        ("KeymapWrapper: OnKeysChanged, aGdkKeymap=%p, aKeymapWrapper=%p",
+         aGdkKeymap, aKeymapWrapper));
+
+    MOZ_ASSERT(sInstance == aKeymapWrapper,
+               "This instance must be the singleton instance");
+
+    // We cannot reintialize here becasue we don't have GdkWindow which is using
+    // the GdkKeymap.  We'll reinitialize it when next GetInstance() is called.
+    sInstance->mInitialized = false;
+}
+
+} // namespace widget
+} // namespace mozilla
diff --git a/widget/gtk2/nsGtkKeyUtils.h b/widget/gtk2/nsGtkKeyUtils.h
index 36868a0c2aa9..3041bf5fec3b 100644
--- a/widget/gtk2/nsGtkKeyUtils.h
+++ b/widget/gtk2/nsGtkKeyUtils.h
@@ -39,8 +39,63 @@
 #ifndef __nsGdkKeyUtils_h__
 #define __nsGdkKeyUtils_h__
 
+#include "nsEvent.h"
+
+#include <gdk/gdk.h>
+
 int      GdkKeyCodeToDOMKeyCode     (int aKeysym);
 int      DOMKeyCodeToGdkKeyCode     (int aKeysym);
 PRUint32 nsConvertCharCodeToUnicode (GdkEventKey* aEvent);
 
+namespace mozilla {
+namespace widget {
+
+/**
+ *  KeymapWrapper is a wrapper class of GdkKeymap.  GdkKeymap doesn't support
+ *  all our needs, therefore, we need to access lower level APIs.
+ *  But such code is usually complex and might be slow.  Against such issues,
+ *  we should cache some information.
+ *
+ *  This class provides only static methods.  The methods is using internal
+ *  singleton instance which is initialized by default GdkKeymap.  When the
+ *  GdkKeymap is destroyed, the singleton instance will be destroyed.
+ */
+
+class KeymapWrapper
+{
+protected:
+
+    /**
+     * GetInstance() returns a KeymapWrapper instance.
+     *
+     * @return                  A singleton instance of KeymapWrapper.
+     */
+    static KeymapWrapper* GetInstance();
+
+    KeymapWrapper();
+    ~KeymapWrapper();
+
+    bool mInitialized;
+
+    /**
+     * mGdkKeymap is a wrapped instance by this class.
+     */
+    GdkKeymap* mGdkKeymap;
+
+    /**
+     * Pointer of the singleton instance.
+     */
+    static KeymapWrapper* sInstance;
+
+    /**
+     * Signal handlers.
+     */
+    static void OnKeysChanged(GdkKeymap* aKeymap, KeymapWrapper* aKeymapWrapper);
+    static void OnDestroyKeymap(KeymapWrapper* aKeymapWrapper,
+                                GdkKeymap *aGdkKeymap);
+};
+
+} // namespace widget
+} // namespace mozilla
+
 #endif /* __nsGdkKeyUtils_h__ */