FIX: handle mouseCaptureLost in common ctrls

Change-Id: Ifde2406911a628fa61acf41c0e7a5120612d73bf

src/slic3r/GUI/Widgets/DropDown.hpp

@@ -98,6 +98,7 @@ private:
     // some useful events
     void mouseDown(wxMouseEvent& event);
     void mouseReleased(wxMouseEvent &event);
+    void mouseCaptureLost(wxMouseCaptureLostEvent &event);
     void mouseMove(wxMouseEvent &event);
     void mouseWheelMoved(wxMouseEvent &event);