diff --git a/src/db/db/dbInstances.cc b/src/db/db/dbInstances.cc
index 4f1a8ca54..12804e249 100644
--- a/src/db/db/dbInstances.cc
+++ b/src/db/db/dbInstances.cc
@@ -280,12 +280,18 @@ void
 instance_iterator<Traits>::release_iter ()
 { 
   if (m_type == TInstance) {
-    if (m_stable) {
+    if (m_stable && ! m_unsorted) {
       if (m_with_props) {
         basic_iter (cell_inst_wp_array_type::tag (), InstancesEditableTag ()).~stable_iter_wp_type ();
       } else {
         basic_iter (cell_inst_array_type::tag (), InstancesEditableTag ()).~stable_iter_type ();
       }
+    } else if (m_stable) {
+      if (m_with_props) {
+        basic_unsorted_iter (cell_inst_wp_array_type::tag (), InstancesEditableTag ()).~stable_unsorted_iter_wp_type ();
+      } else {
+        basic_unsorted_iter (cell_inst_array_type::tag (), InstancesEditableTag ()).~stable_unsorted_iter_type ();
+      }
     } else {
       if (m_with_props) {
         basic_iter (cell_inst_wp_array_type::tag (), InstancesNonEditableTag ()).~iter_wp_type ();
@@ -301,12 +307,18 @@ void
 instance_iterator<Traits>::make_iter ()
 { 
   if (m_type == TInstance) {
-    if (m_stable) {
+    if (m_stable && ! m_unsorted) {
       if (m_with_props) {
         new (&basic_iter (cell_inst_wp_array_type::tag (), InstancesEditableTag ())) stable_iter_wp_type ();
       } else {
         new (&basic_iter (cell_inst_array_type::tag (), InstancesEditableTag ())) stable_iter_type ();
       }
+    } else if (m_stable) {
+      if (m_with_props) {
+        new (&basic_unsorted_iter (cell_inst_wp_array_type::tag (), InstancesEditableTag ())) stable_unsorted_iter_wp_type ();
+      } else {
+        new (&basic_unsorted_iter (cell_inst_array_type::tag (), InstancesEditableTag ())) stable_unsorted_iter_type ();
+      }
     } else {
       if (m_with_props) {
         new (&basic_iter (cell_inst_wp_array_type::tag (), InstancesNonEditableTag ())) iter_wp_type ();
@@ -322,18 +334,24 @@ template <class Traits>
 bool
 instance_iterator<Traits>::operator== (const instance_iterator<Traits> &d) const
 {
-  if (! (m_type == d.m_type && m_stable == d.m_stable && m_with_props == d.m_with_props)) {
+  if (! (m_type == d.m_type && m_stable == d.m_stable && m_with_props == d.m_with_props && m_unsorted == d.m_unsorted)) {
     return false;
   }
   if (m_type == TNull) {
     return true;
   } else {
     if (m_stable) {
-      if (m_with_props) {
+      if (m_with_props && ! m_unsorted) {
         return (basic_iter (cell_inst_wp_array_type::tag (), InstancesEditableTag ()) == d.basic_iter (cell_inst_wp_array_type::tag (), InstancesEditableTag ()));
       } else {
         return (basic_iter (cell_inst_array_type::tag (), InstancesEditableTag ()) == d.basic_iter (cell_inst_array_type::tag (), InstancesEditableTag ()));
       }
+    } else if (m_stable) {
+      if (m_with_props) {
+        return (basic_unsorted_iter (cell_inst_wp_array_type::tag (), InstancesEditableTag ()) == d.basic_unsorted_iter (cell_inst_wp_array_type::tag (), InstancesEditableTag ()));
+      } else {
+        return (basic_unsorted_iter (cell_inst_array_type::tag (), InstancesEditableTag ()) == d.basic_unsorted_iter (cell_inst_array_type::tag (), InstancesEditableTag ()));
+      }
     } else {
       if (m_with_props) {
         return (basic_iter (cell_inst_wp_array_type::tag (), InstancesNonEditableTag ()) == d.basic_iter (cell_inst_wp_array_type::tag (), InstancesNonEditableTag ()));
@@ -355,16 +373,23 @@ instance_iterator<Traits>::operator= (const instance_iterator<Traits> &iter)
     m_type = iter.m_type;
     m_stable = iter.m_stable;
     m_with_props = iter.m_with_props;
+    m_unsorted = iter.m_unsorted;
     m_traits = iter.m_traits;
 
     if (m_type == TInstance) {
 
-      if (m_stable) {
+      if (m_stable && ! m_unsorted) {
         if (m_with_props) {
           new (&basic_iter (cell_inst_wp_array_type::tag (), InstancesEditableTag ())) stable_iter_wp_type (iter.basic_iter (cell_inst_wp_array_type::tag (), InstancesEditableTag ()));
         } else {
           new (&basic_iter (cell_inst_array_type::tag (), InstancesEditableTag ())) stable_iter_type (iter.basic_iter (cell_inst_array_type::tag (), InstancesEditableTag ()));
         }
+      } else if (m_stable) {
+        if (m_with_props) {
+          new (&basic_unsorted_iter (cell_inst_wp_array_type::tag (), InstancesEditableTag ())) stable_unsorted_iter_wp_type (iter.basic_unsorted_iter (cell_inst_wp_array_type::tag (), InstancesEditableTag ()));
+        } else {
+          new (&basic_unsorted_iter (cell_inst_array_type::tag (), InstancesEditableTag ())) stable_unsorted_iter_type (iter.basic_unsorted_iter (cell_inst_array_type::tag (), InstancesEditableTag ()));
+        }
       } else {
         if (m_with_props) {
           new (&basic_iter (cell_inst_wp_array_type::tag (), InstancesNonEditableTag ())) iter_wp_type (iter.basic_iter (cell_inst_wp_array_type::tag (), InstancesNonEditableTag ()));
@@ -387,12 +412,18 @@ db::Box
 instance_iterator<Traits>::quad_box () const
 {
   if (m_type == TInstance) {
-    if (m_stable) {
+    if (m_stable && ! m_unsorted) {
       if (m_with_props) {
         return m_traits.quad_box (basic_iter (cell_inst_wp_array_type::tag (), InstancesEditableTag ()));
       } else {
         return m_traits.quad_box (basic_iter (cell_inst_array_type::tag (), InstancesEditableTag ()));
       }
+    } else if (m_stable) {
+      if (m_with_props) {
+        return m_traits.quad_box (basic_unsorted_iter (cell_inst_wp_array_type::tag (), InstancesEditableTag ()));
+      } else {
+        return m_traits.quad_box (basic_unsorted_iter (cell_inst_array_type::tag (), InstancesEditableTag ()));
+      }
     } else {
       if (m_with_props) {
         return m_traits.quad_box (basic_iter (cell_inst_wp_array_type::tag (), InstancesNonEditableTag ()));
@@ -409,12 +440,18 @@ size_t
 instance_iterator<Traits>::quad_id () const
 {
   if (m_type == TInstance) {
-    if (m_stable) {
+    if (m_stable && ! m_unsorted) {
       if (m_with_props) {
         return m_traits.quad_id (basic_iter (cell_inst_wp_array_type::tag (), InstancesEditableTag ()));
       } else {
         return m_traits.quad_id (basic_iter (cell_inst_array_type::tag (), InstancesEditableTag ()));
       }
+    } else if (m_stable) {
+      if (m_with_props) {
+        return m_traits.quad_id (basic_unsorted_iter (cell_inst_wp_array_type::tag (), InstancesEditableTag ()));
+      } else {
+        return m_traits.quad_id (basic_unsorted_iter (cell_inst_array_type::tag (), InstancesEditableTag ()));
+      }
     } else {
       if (m_with_props) {
         return m_traits.quad_id (basic_iter (cell_inst_wp_array_type::tag (), InstancesNonEditableTag ()));
@@ -431,12 +468,18 @@ void
 instance_iterator<Traits>::skip_quad () 
 {
   if (m_type == TInstance) {
-    if (m_stable) {
+    if (m_stable && ! m_unsorted) {
       if (m_with_props) {
         m_traits.skip_quad (basic_iter (cell_inst_wp_array_type::tag (), InstancesEditableTag ()));
       } else {
         m_traits.skip_quad (basic_iter (cell_inst_array_type::tag (), InstancesEditableTag ()));
       }
+    } else if (m_stable) {
+      if (m_with_props) {
+        m_traits.skip_quad (basic_unsorted_iter (cell_inst_wp_array_type::tag (), InstancesEditableTag ()));
+      } else {
+        m_traits.skip_quad (basic_unsorted_iter (cell_inst_array_type::tag (), InstancesEditableTag ()));
+      }
     } else {
       if (m_with_props) {
         m_traits.skip_quad (basic_iter (cell_inst_wp_array_type::tag (), InstancesNonEditableTag ()));
@@ -454,12 +497,18 @@ instance_iterator<Traits> &
 instance_iterator<Traits>::operator++() 
 {
   if (m_type == TInstance) {
-    if (m_stable) {
+    if (m_stable && ! m_unsorted) {
       if (m_with_props) {
         ++basic_iter (cell_inst_wp_array_type::tag (), InstancesEditableTag ());
       } else {
         ++basic_iter (cell_inst_array_type::tag (), InstancesEditableTag ());
       }
+    } else if (m_stable) {
+      if (m_with_props) {
+        ++basic_unsorted_iter (cell_inst_wp_array_type::tag (), InstancesEditableTag ());
+      } else {
+        ++basic_unsorted_iter (cell_inst_array_type::tag (), InstancesEditableTag ());
+      }
     } else {
       if (m_with_props) {
         ++basic_iter (cell_inst_wp_array_type::tag (), InstancesNonEditableTag ());
@@ -478,7 +527,7 @@ void
 instance_iterator<Traits>::make_next () 
 {
   while (true) {
-    if (m_stable) {
+    if (m_stable && ! m_unsorted) {
       if (m_with_props) {
         if (! basic_iter (cell_inst_wp_array_type::tag (), InstancesEditableTag ()).at_end ()) {
           return;
@@ -488,6 +537,16 @@ instance_iterator<Traits>::make_next ()
           return;
         }
       }
+    } else if (m_stable) {
+      if (m_with_props) {
+        if (! basic_unsorted_iter (cell_inst_wp_array_type::tag (), InstancesEditableTag ()).at_end ()) {
+          return;
+        }
+      } else {
+        if (! basic_unsorted_iter (cell_inst_array_type::tag (), InstancesEditableTag ()).at_end ()) {
+          return;
+        }
+      }
     } else {
       if (m_with_props) {
         if (! basic_iter (cell_inst_wp_array_type::tag (), InstancesNonEditableTag ()).at_end ()) {
@@ -514,12 +573,18 @@ void
 instance_iterator<Traits>::update_ref ()
 {
   if (m_type == TInstance) {
-    if (m_stable) {
+    if (m_stable && ! m_unsorted) {
       if (m_with_props) {
         m_ref = m_traits.instance_from_stable_iter (basic_iter (cell_inst_wp_array_type::tag (), InstancesEditableTag ()));
       } else {
         m_ref = m_traits.instance_from_stable_iter (basic_iter (cell_inst_array_type::tag (), InstancesEditableTag ()));
       }
+    } else if (m_stable) {
+      if (m_with_props) {
+        m_ref = m_traits.instance_from_stable_iter (basic_unsorted_iter (cell_inst_wp_array_type::tag (), InstancesEditableTag ()));
+      } else {
+        m_ref = m_traits.instance_from_stable_iter (basic_unsorted_iter (cell_inst_array_type::tag (), InstancesEditableTag ()));
+      }
     } else {
       if (m_with_props) {
         m_ref = value_type (m_traits.instances (), *basic_iter (cell_inst_wp_array_type::tag (), InstancesNonEditableTag ()));
@@ -551,7 +616,7 @@ void
 NormalInstanceIteratorTraits::init (instance_iterator<NormalInstanceIteratorTraits> *iter) const
 {
   tl_assert (mp_insts != 0);
-  if (iter->m_stable) {
+  if (iter->m_stable && ! iter->m_unsorted) {
     if (iter->m_with_props) {
       cell_inst_wp_array_type::tag tag = cell_inst_wp_array_type::tag ();
       iter->basic_iter (tag, InstancesEditableTag ()) = mp_insts->inst_tree (tag, InstancesEditableTag ()).begin_flat ();
@@ -559,6 +624,14 @@ NormalInstanceIteratorTraits::init (instance_iterator<NormalInstanceIteratorTrai
       cell_inst_array_type::tag tag = cell_inst_array_type::tag ();
       iter->basic_iter (tag, InstancesEditableTag ()) = mp_insts->inst_tree (tag, InstancesEditableTag ()).begin_flat ();
     }
+  } else if (iter->m_stable) {
+    if (iter->m_with_props) {
+      cell_inst_wp_array_type::tag tag = cell_inst_wp_array_type::tag ();
+      iter->basic_unsorted_iter (tag, InstancesEditableTag ()) = stable_unsorted_iter_wp_type (mp_insts->inst_tree (tag, InstancesEditableTag ()).begin (), mp_insts->inst_tree (tag, InstancesEditableTag ()).end ());
+    } else {
+      cell_inst_array_type::tag tag = cell_inst_array_type::tag ();
+      iter->basic_unsorted_iter (tag, InstancesEditableTag ()) = stable_unsorted_iter_type (mp_insts->inst_tree (tag, InstancesEditableTag ()).begin (), mp_insts->inst_tree (tag, InstancesEditableTag ()).end ());
+    }
   } else {
     if (iter->m_with_props) {
       cell_inst_wp_array_type::tag tag = cell_inst_wp_array_type::tag ();
diff --git a/src/db/db/dbInstances.h b/src/db/db/dbInstances.h
index 975904e28..a9f11a17d 100644
--- a/src/db/db/dbInstances.h
+++ b/src/db/db/dbInstances.h
@@ -527,7 +527,9 @@ public:
   typedef typename IterTraits::iter_wp_type iter_wp_type;
   typedef typename IterTraits::stable_iter_type stable_iter_type;
   typedef typename IterTraits::stable_iter_wp_type stable_iter_wp_type;
-  typedef const value_type *pointer; 
+  typedef typename IterTraits::stable_unsorted_iter_type stable_unsorted_iter_type;
+  typedef typename IterTraits::stable_unsorted_iter_wp_type stable_unsorted_iter_wp_type;
+  typedef const value_type *pointer;
   typedef value_type reference;   //  operator* returns a value
   typedef std::forward_iterator_tag iterator_category;
   typedef void difference_type;
@@ -541,7 +543,7 @@ public:
    *  @brief Default ctor
    */
   instance_iterator ()
-    : m_with_props (false), m_stable (false), m_type (TNull), m_traits ()
+    : m_type (TNull), m_with_props (false), m_stable (false), m_unsorted (false), m_traits ()
   { }
 
   /**
@@ -556,7 +558,7 @@ public:
    *  @brief Constructor
    */
   instance_iterator (const IterTraits &traits)
-    : m_with_props (false), m_stable (traits.instances ()->is_editable ()), m_type (TInstance), m_traits (traits)
+    : m_type (TInstance), m_with_props (false), m_stable (traits.instances ()->is_editable ()), m_unsorted (traits.instances ()->instance_tree_needs_sort ()), m_traits (traits)
   { 
     make_iter ();
     make_next ();
@@ -567,7 +569,7 @@ public:
    *  @brief Copy constructor
    */
   instance_iterator (const instance_iterator &iter)
-    : m_with_props (false), m_stable (false), m_type (TNull), m_traits ()
+    : m_type (TNull), m_with_props (false), m_stable (false), m_unsorted (false), m_traits ()
   {
     operator= (iter);
   }
@@ -661,7 +663,7 @@ public:
    */
   stable_iter_type &basic_iter (cell_inst_array_type::tag, InstancesEditableTag)
   {
-    tl_assert (m_type == TInstance && m_stable == true && m_with_props == false);
+    tl_assert (m_type == TInstance && m_stable == true && m_with_props == false && m_unsorted == false);
     return *((stable_iter_type *) m_generic.stable_iter);
   }
 
@@ -670,10 +672,28 @@ public:
    */
   const stable_iter_type &basic_iter (cell_inst_array_type::tag, InstancesEditableTag) const
   {
-    tl_assert (m_type == TInstance && m_stable == true && m_with_props == false);
+    tl_assert (m_type == TInstance && m_stable == true && m_with_props == false && m_unsorted == false);
     return *((stable_iter_type *) m_generic.stable_iter);
   }
 
+  /**
+   *  @brief Gets the basic iterator in the editable case without properties and in the unsorted case
+   */
+  stable_unsorted_iter_type &basic_unsorted_iter (cell_inst_array_type::tag, InstancesEditableTag)
+  {
+    tl_assert (m_type == TInstance && m_stable == true && m_with_props == false && m_unsorted == true);
+    return *((stable_unsorted_iter_type *) m_generic.stable_unsorted_iter);
+  }
+
+  /**
+   *  @brief Gets the basic iterator in the editable case without properties and in the unsorted case (const version)
+   */
+  const stable_unsorted_iter_type &basic_unsorted_iter (cell_inst_array_type::tag, InstancesEditableTag) const
+  {
+    tl_assert (m_type == TInstance && m_stable == true && m_with_props == false && m_unsorted == true);
+    return *((stable_unsorted_iter_type *) m_generic.stable_unsorted_iter);
+  }
+
   /**
    *  @brief Gets the basic iterator in the non-editable case with properties
    */
@@ -697,7 +717,7 @@ public:
    */
   stable_iter_wp_type &basic_iter (cell_inst_wp_array_type::tag, InstancesEditableTag)
   {
-    tl_assert (m_type == TInstance && m_stable == true && m_with_props == true);
+    tl_assert (m_type == TInstance && m_stable == true && m_with_props == true && m_unsorted == false);
     return *((stable_iter_wp_type *) m_generic.pstable_iter);
   }
 
@@ -706,10 +726,28 @@ public:
    */
   const stable_iter_wp_type &basic_iter (cell_inst_wp_array_type::tag, InstancesEditableTag) const
   {
-    tl_assert (m_type == TInstance && m_stable == true && m_with_props == true);
+    tl_assert (m_type == TInstance && m_stable == true && m_with_props == true && m_unsorted == false);
     return *((stable_iter_wp_type *) m_generic.pstable_iter);
   }
 
+  /**
+   *  @brief Gets the basic iterator in the editable case with properties and in the unsorted case
+   */
+  stable_unsorted_iter_wp_type &basic_unsorted_iter (cell_inst_wp_array_type::tag, InstancesEditableTag)
+  {
+    tl_assert (m_type == TInstance && m_stable == true && m_with_props == true && m_unsorted == true);
+    return *((stable_unsorted_iter_wp_type *) m_generic.pstable_unsorted_iter);
+  }
+
+  /**
+   *  @brief Gets the basic iterator in the editable case with properties and in the unsorted case (const version)
+   */
+  const stable_unsorted_iter_wp_type &basic_unsorted_iter (cell_inst_wp_array_type::tag, InstancesEditableTag) const
+  {
+    tl_assert (m_type == TInstance && m_stable == true && m_with_props == true && m_unsorted == true);
+    return *((stable_unsorted_iter_wp_type *) m_generic.pstable_unsorted_iter);
+  }
+
 private:
   friend struct NormalInstanceIteratorTraits;
   friend struct OverlappingInstanceIteratorTraits;
@@ -720,11 +758,14 @@ private:
     char piter[sizeof (iter_wp_type)];
     char stable_iter[sizeof (stable_iter_type)];
     char pstable_iter[sizeof (stable_iter_wp_type)];
+    char stable_unsorted_iter[sizeof (stable_unsorted_iter_type)];
+    char pstable_unsorted_iter[sizeof (stable_unsorted_iter_wp_type)];
   } m_generic;
 
-  bool m_with_props : 8;
-  bool m_stable : 8;
   object_type m_type : 16;
+  bool m_with_props : 1;
+  bool m_stable : 1;
+  bool m_unsorted : 1;
   value_type m_ref;
   IterTraits m_traits;
 
@@ -759,6 +800,8 @@ struct DB_PUBLIC NormalInstanceIteratorTraits
   typedef tl::iterator_pair<cell_inst_wp_tree_type::const_iterator> iter_wp_type;
   typedef stable_cell_inst_tree_type::flat_iterator stable_iter_type;
   typedef stable_cell_inst_wp_tree_type::flat_iterator stable_iter_wp_type;
+  typedef tl::iterator_pair<stable_cell_inst_tree_type::const_iterator> stable_unsorted_iter_type;
+  typedef tl::iterator_pair<stable_cell_inst_wp_tree_type::const_iterator> stable_unsorted_iter_wp_type;
 
   NormalInstanceIteratorTraits ();
   NormalInstanceIteratorTraits (const instances_type *insts);
@@ -804,6 +847,8 @@ struct DB_PUBLIC TouchingInstanceIteratorTraits
   typedef cell_inst_wp_tree_type::touching_iterator iter_wp_type;
   typedef stable_cell_inst_tree_type::touching_iterator stable_iter_type;
   typedef stable_cell_inst_wp_tree_type::touching_iterator stable_iter_wp_type;
+  typedef stable_iter_type stable_unsorted_iter_type;
+  typedef stable_iter_wp_type stable_unsorted_iter_wp_type;
 
   TouchingInstanceIteratorTraits ();
   TouchingInstanceIteratorTraits (const instances_type *insts, const box_type &box, const layout_type *layout);
@@ -855,6 +900,8 @@ struct DB_PUBLIC OverlappingInstanceIteratorTraits
   typedef cell_inst_wp_tree_type::overlapping_iterator iter_wp_type;
   typedef stable_cell_inst_tree_type::overlapping_iterator stable_iter_type;
   typedef stable_cell_inst_wp_tree_type::overlapping_iterator stable_iter_wp_type;
+  typedef stable_iter_type stable_unsorted_iter_type;
+  typedef stable_iter_wp_type stable_unsorted_iter_wp_type;
 
   OverlappingInstanceIteratorTraits ();
   OverlappingInstanceIteratorTraits (const instances_type *insts, const box_type &box, const layout_type *layout);
@@ -1741,6 +1788,7 @@ private:
   friend struct NormalInstanceIteratorTraits;
   friend struct TouchingInstanceIteratorTraits;
   friend struct OverlappingInstanceIteratorTraits;
+  template <class Traits> friend class instance_iterator;
   template <class Inst, class ET> friend class InstOp;
 
   union {
@@ -1773,7 +1821,7 @@ private:
   }
 
   /**
-   *  @brief Sets a flag indicating that the instance tree needs sorting
+   *  @brief Gets a flag indicating that the instance tree needs sorting
    */
   bool instance_tree_needs_sort () const
   {
diff --git a/src/db/unit_tests/dbLayoutTests.cc b/src/db/unit_tests/dbLayoutTests.cc
index 6bd145478..02d26a22d 100644
--- a/src/db/unit_tests/dbLayoutTests.cc
+++ b/src/db/unit_tests/dbLayoutTests.cc
@@ -28,6 +28,7 @@
 #include "dbTextWriter.h"
 #include "dbCellMapping.h"
 #include "dbInstElement.h"
+#include "dbWriter.h"
 #include "tlString.h"
 #include "tlUnitTest.h"
 
@@ -872,6 +873,68 @@ TEST(11_FindPath)
   EXPECT_EQ (d, "cell_index=1 r90 *1 0,0;cell_index=2 r0 *1 100,200");
 }
 
+//  Shapes can be flat-iterated even in locked layout
+TEST(12_ShapesInLockedLayout)
+{
+  db::Layout l;
+  db::Cell &top = l.cell (l.add_cell ("TOP"));
+  unsigned int l1 = l.insert_layer (db::LayerProperties (1, 0));
+
+  {
+    db::LayoutLocker locker (&l);
+    EXPECT_EQ (l.under_construction (), true);
+
+    top.shapes (l1).insert (db::Box (1, 2, 3, 4));
+    top.shapes (l1).insert (db::Box (10, 20, 30, 40));
+    top.shapes (l1).insert (db::Box (100, 200, 300, 400));
+
+    double a = 0;
+    for (auto s = top.shapes (l1).begin (db::ShapeIterator::All); ! s.at_end (); ++s) {
+      a += s->area ();
+    }
+    EXPECT_EQ (a, 40404.0);
+  }
+
+  EXPECT_EQ (l.under_construction (), false);
+
+  double a = 0;
+  for (auto s = top.shapes (l1).begin (db::ShapeIterator::All); ! s.at_end (); ++s) {
+    a += s->area ();
+  }
+  EXPECT_EQ (a, 40404.0);
+}
+
+//  Instances can be flat-iterated even in locked layout
+TEST(13_InstancesInLockedLayout)
+{
+  db::Layout l;
+  db::Cell &top = l.cell (l.add_cell ("TOP"));
+  db::Cell &c = l.cell (l.add_cell ("C"));
+
+  {
+    db::LayoutLocker locker (&l);
+    EXPECT_EQ (l.under_construction (), true);
+
+    top.insert (db::CellInstArray (c.cell_index (), db::Trans (db::Vector (10, 20))));
+    top.insert (db::CellInstArray (c.cell_index (), db::Trans (db::Vector (100, 200))));
+    top.insert (db::CellInstArray (c.cell_index (), db::Trans (db::Vector (1, 2))));
+
+    db::Vector a;
+    for (auto i = top.begin (); ! i.at_end (); ++i) {
+      a += i->cell_inst ().front ().disp ();
+    }
+    EXPECT_EQ (a.to_string (), "111,222");
+  }
+
+  EXPECT_EQ (l.under_construction (), false);
+
+  db::Vector a;
+  for (auto i = top.begin (); ! i.at_end (); ++i) {
+    a += i->cell_inst ().front ().disp ();
+  }
+  EXPECT_EQ (a.to_string (), "111,222");
+}
+
 //  issue #1860
 TEST(100_UndoOfDeleteLayer)
 {