FIX:fixed the mall system dialog not being destroyed

Change-Id: Ie453bdbb41e59da69987e24a7c2d5cc9f378aee4

src/slic3r/GUI/MainFrame.cpp

@@ -449,6 +449,8 @@ DPIFrame(NULL, wxID_ANY, "", wxDefaultPosition, wxDefaultSize, BORDERLESS_FRAME_
         m_plater->reset();
         this->shutdown();
         // propagate event
+
+        wxGetApp().remove_mall_system_dialog();
         event.Skip();
         BOOST_LOG_TRIVIAL(info) << __FUNCTION__<< ": mainframe finished process close_widow event";
     });