Fixed context menu showing up when user right clicks on 3D scene and release the mouse button after dragging over the objects list

src/slic3r/GUI/GLCanvas3D.hpp

@@ -624,6 +624,8 @@ public:
     bool has_toolpaths_to_export() const;
     void export_toolpaths_to_obj(const char* filename) const;
 
+    void mouse_up_cleanup();
+
 private:
     bool _is_shown_on_screen() const;