[EXPLORER] Do WM_MOUSEACTIVATE.MA_NOACTIVATE on notification area

Don't activate taskbar when clicked the notification area.
CORE-10667

base/shell/explorer/trayntfy.cpp

@@ -124,6 +124,11 @@ class CTrayNotifyWnd :
         return TRUE;
     }
 
+    LRESULT OnMouseActivate(UINT uMsg, WPARAM wParam, LPARAM lParam, BOOL& bHandled)
+    {
+        return MA_NOACTIVATE;
+    }
+
     BOOL GetMinimumSize(IN OUT PSIZE pSize)
     {
         SIZE szClock = { 0, 0 };
@@ -345,6 +350,7 @@ class CTrayNotifyWnd :
 
     BEGIN_MSG_MAP(CTrayNotifyWnd)
         MESSAGE_HANDLER(WM_CREATE, OnCreate)
+        MESSAGE_HANDLER(WM_MOUSEACTIVATE, OnMouseActivate)
         MESSAGE_HANDLER(WM_THEMECHANGED, OnThemeChanged)
         MESSAGE_HANDLER(WM_ERASEBKGND, OnEraseBackground)
         MESSAGE_HANDLER(WM_SIZE, OnSize)