skins2(Win32): remove an unneeded WS_EX_TOOLWINDOW option

This option prevents windows from being displayed in the alt-tab list.
This should fix trac #4343 for Vista and Win7  (to be tested)
(cherry picked from commit 6c74b935f99b9d46bb92b3ba01bfbaf4c7d52276)

modules/gui/skins2/win32/win32_window.cpp

@@ -75,7 +75,7 @@ Win32Window::Win32Window( intf_thread_t *pIntf, GenericWindow &rWindow,
     {
         // top-level window (owned by the root window)
         HWND hWnd_owner = pFactory->getParentWindow();
-        m_hWnd = CreateWindowEx( WS_EX_TOOLWINDOW, "SkinWindowClass",
+        m_hWnd = CreateWindowEx( 0, "SkinWindowClass",
             "default name", WS_POPUP | WS_CLIPCHILDREN,
             0, 0, 0, 0, hWnd_owner, 0, hInst, NULL );
     }