Index: base/shell/explorer/traywnd.cpp
===================================================================
--- base/shell/explorer/traywnd.cpp	(revision 74919)
+++ base/shell/explorer/traywnd.cpp	(working copy)
@@ -61,6 +61,8 @@
 
 const GUID IID_IShellDesktopTray = { 0x213e2df9, 0x9a14, 0x4328, { 0x99, 0xb1, 0x69, 0x61, 0xf9, 0x14, 0x3c, 0xe9 } };
 
+static WNDPROC s_orgWndProc;
+
 class CStartButton
     : public CWindow
 {
@@ -68,6 +70,20 @@
     SIZE       m_Size;
     HFONT      m_Font;
 
+    static LRESULT CALLBACK StartButtonWndProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam, UINT_PTR uIdSubclass, DWORD_PTR dwRefData)
+    {
+        switch (uMsg)
+        {
+        case WM_LBUTTONDOWN:
+             ::SendMessageW(::GetParent(hWnd), TWM_OPENSTARTMENU, 0, 0);
+             return TRUE;
+        case WM_LBUTTONUP:
+             return TRUE;
+        default:
+             return CallWindowProc(s_orgWndProc, hWnd, uMsg, wParam, lParam);
+        } 
+    }
+
 public:
     CStartButton()
         : m_ImageList(NULL),
@@ -127,6 +143,9 @@
     {
         SetWindowTheme(m_hWnd, L"Start", NULL);
 
+        s_orgWndProc = (WNDPROC)GetWindowLongPtr(GWLP_WNDPROC);
+        SetWindowLongPtr(GWLP_WNDPROC, (LONG_PTR)StartButtonWndProc);
+
         m_ImageList = ImageList_LoadImageW(hExplorerInstance,
                                            MAKEINTRESOURCEW(IDB_START),
                                            0, 0, 0,