FIX:fixed appconfig is not saved when switching dark mode

Change-Id: I77fc3808309a23497000c34b6047a359d12c4622

src/slic3r/GUI/Notebook.cpp

@@ -49,7 +49,6 @@ ButtonsListCtrl::ButtonsListCtrl(wxWindow *parent, wxBoxSizer* side_tools) :
     // BBS: disable custom paint
     //this->Bind(wxEVT_PAINT, &ButtonsListCtrl::OnPaint, this);
     Bind(wxEVT_SYS_COLOUR_CHANGED, [this](auto& e){
-        auto a = 10;
     });
 }