Check for existence of gcode toolpaths that can be exported to obj file

src/slic3r/GUI/GLCanvas3D.cpp

@@ -3403,6 +3403,11 @@ void GLCanvas3D::msw_rescale()
     m_warning_texture.msw_rescale(*this);
 }
 
+bool GLCanvas3D::has_toolpaths_to_export() const
+{
+    return m_volumes.has_toolpaths_to_export();
+}
+
 void GLCanvas3D::export_toolpaths_to_obj(const char* filename) const
 {
     m_volumes.export_toolpaths_to_obj(filename);