diff --git a/src/slic3r/GUI/GUI_ObjectManipulation.cpp b/src/slic3r/GUI/GUI_ObjectManipulation.cpp
index 224c053e4..310000ecc 100644
--- a/src/slic3r/GUI/GUI_ObjectManipulation.cpp
+++ b/src/slic3r/GUI/GUI_ObjectManipulation.cpp
@@ -216,9 +216,10 @@ ObjectManipulation::ObjectManipulation(wxWindow* parent) :
                 else
                     return;
 
+                // Update mirroring at the GLVolumes.
                 selection.synchronize_unselected_instances(Selection::SYNC_ROTATION_GENERAL);
                 selection.synchronize_unselected_volumes();
-
+                // Copy mirroring values from GLVolumes into Model (ModelInstance / ModelVolume), trigger background processing.
                 canvas->do_mirror();
                 canvas->set_as_dirty();
                 UpdateAndShow(true);
@@ -297,8 +298,10 @@ ObjectManipulation::ObjectManipulation(wxWindow* parent) :
                     else
                         return;
 
+                    // Update rotation at the GLVolumes.
                     selection.synchronize_unselected_instances(Selection::SYNC_ROTATION_GENERAL);
                     selection.synchronize_unselected_volumes();
+                    // Copy rotation values from GLVolumes into Model (ModelInstance / ModelVolume), trigger background processing.
                     canvas->do_rotate();
 
                     UpdateAndShow(true);