diff --git a/src/PrusaSlicer.cpp b/src/PrusaSlicer.cpp
index e5c6689be..a28fa3104 100644
--- a/src/PrusaSlicer.cpp
+++ b/src/PrusaSlicer.cpp
@@ -53,6 +53,8 @@
     #include "slic3r/GUI/3DScene.hpp"
     #include "slic3r/GUI/InstanceCheck.hpp" 
     #include "slic3r/GUI/AppConfig.hpp" 
+    #include "slic3r/GUI/MainFrame.hpp"
+    #include "slic3r/GUI/Plater.hpp"
 #endif /* SLIC3R_GUI */
 
 using namespace Slic3r;
diff --git a/src/libslic3r/Fill/FillBase.hpp b/src/libslic3r/Fill/FillBase.hpp
index 083cb86ce..2e9b64735 100644
--- a/src/libslic3r/Fill/FillBase.hpp
+++ b/src/libslic3r/Fill/FillBase.hpp
@@ -11,13 +11,13 @@
 
 #include "../libslic3r.h"
 #include "../BoundingBox.hpp"
-#include "../PrintConfig.hpp"
 #include "../Utils.hpp"
 
 namespace Slic3r {
 
 class ExPolygon;
 class Surface;
+enum InfillPattern : int;
 
 class InfillFailedException : public std::runtime_error {
 public:
diff --git a/src/libslic3r/Model.cpp b/src/libslic3r/Model.cpp
index 0f1c346a6..19973cb9b 100644
--- a/src/libslic3r/Model.cpp
+++ b/src/libslic3r/Model.cpp
@@ -455,24 +455,19 @@ bool Model::looks_like_imperial_units() const
     if (this->objects.size() == 0)
         return false;
 
-    stl_vertex size = this->objects[0]->get_object_stl_stats().size;
+    for (ModelObject* obj : this->objects)
+        if (obj->get_object_stl_stats().volume < 9.0) // 9 = 3*3*3;
+            return true;
 
-    for (ModelObject* o : this->objects) {
-        auto sz = o->get_object_stl_stats().size;
-
-        if (size[0] < sz[0]) size[0] = sz[0];
-        if (size[1] < sz[1]) size[1] = sz[1];
-        if (size[2] < sz[2]) size[2] = sz[2];
-    }
-
-    return (size[0] < 3 && size[1] < 3 && size[2] < 3);
+    return false;
 }
 
 void Model::convert_from_imperial_units()
 {
     double in_to_mm = 25.4;
-    for (ModelObject* o : this->objects)
-        o->scale_mesh_after_creation(Vec3d(in_to_mm, in_to_mm, in_to_mm));
+    for (ModelObject* obj : this->objects)
+        if (obj->get_object_stl_stats().volume < 9.0) // 9 = 3*3*3;
+            obj->scale_mesh_after_creation(Vec3d(in_to_mm, in_to_mm, in_to_mm));
 }
 
 void Model::adjust_min_z()
@@ -1273,6 +1268,27 @@ void ModelObject::split(ModelObjectPtrs* new_objects)
     return;
 }
 
+void ModelObject::merge()
+{
+    if (this->volumes.size() == 1) {
+        // We can't merge meshes if there's just one volume
+        return;
+    }
+
+    TriangleMesh mesh;
+
+    for (ModelVolume* volume : volumes)
+        if (!volume->mesh().empty())
+            mesh.merge(volume->mesh());
+    mesh.repair();
+
+    this->clear_volumes();
+    ModelVolume* vol = this->add_volume(mesh);
+
+    if (!vol)
+        return;
+}
+
 // Support for non-uniform scaling of instances. If an instance is rotated by angles, which are not multiples of ninety degrees,
 // then the scaling in world coordinate system is not representable by the Geometry::Transformation structure.
 // This situation is solved by baking in the instance transformation into the mesh vertices.
diff --git a/src/libslic3r/Model.hpp b/src/libslic3r/Model.hpp
index f7b63bff4..e5930fb8a 100644
--- a/src/libslic3r/Model.hpp
+++ b/src/libslic3r/Model.hpp
@@ -287,6 +287,7 @@ public:
     bool needed_repair() const;
     ModelObjectPtrs cut(size_t instance, coordf_t z, bool keep_upper = true, bool keep_lower = true, bool rotate_lower = false);    // Note: z is in world coordinates
     void split(ModelObjectPtrs* new_objects);
+    void merge();
     // Support for non-uniform scaling of instances. If an instance is rotated by angles, which are not multiples of ninety degrees,
     // then the scaling in world coordinate system is not representable by the Geometry::Transformation structure.
     // This situation is solved by baking in the instance transformation into the mesh vertices.
diff --git a/src/libslic3r/ModelArrange.cpp b/src/libslic3r/ModelArrange.cpp
index 85aa25a5f..230b04de5 100644
--- a/src/libslic3r/ModelArrange.cpp
+++ b/src/libslic3r/ModelArrange.cpp
@@ -1,4 +1,6 @@
 #include "ModelArrange.hpp"
+
+#include <libslic3r/Model.hpp>
 #include "MTUtils.hpp"
 
 namespace Slic3r {
diff --git a/src/libslic3r/ModelArrange.hpp b/src/libslic3r/ModelArrange.hpp
index d65b0fd6d..afe146d43 100644
--- a/src/libslic3r/ModelArrange.hpp
+++ b/src/libslic3r/ModelArrange.hpp
@@ -1,11 +1,14 @@
 #ifndef MODELARRANGE_HPP
 #define MODELARRANGE_HPP
 
-#include <libslic3r/Model.hpp>
 #include <libslic3r/Arrange.hpp>
 
 namespace Slic3r {
 
+class Model;
+class ModelInstance;
+using ModelInstancePtrs = std::vector<ModelInstance*>;
+
 using arrangement::ArrangePolygon;
 using arrangement::ArrangePolygons;
 using arrangement::ArrangeParams;
diff --git a/src/libslic3r/PrintConfig.hpp b/src/libslic3r/PrintConfig.hpp
index 10ff8086c..4fc3d2d27 100644
--- a/src/libslic3r/PrintConfig.hpp
+++ b/src/libslic3r/PrintConfig.hpp
@@ -33,7 +33,7 @@ enum PrintHostType {
     htOctoPrint, htDuet, htFlashAir, htAstroBox
 };
 
-enum InfillPattern {
+enum InfillPattern : int {
     ipRectilinear, ipMonotonous, ipGrid, ipTriangles, ipStars, ipCubic, ipLine, ipConcentric, ipHoneycomb, ip3DHoneycomb,
     ipGyroid, ipHilbertCurve, ipArchimedeanChords, ipOctagramSpiral, ipCount,
 };
diff --git a/src/libslic3r/Slicing.hpp b/src/libslic3r/Slicing.hpp
index 95cf6891b..2fd609b2c 100644
--- a/src/libslic3r/Slicing.hpp
+++ b/src/libslic3r/Slicing.hpp
@@ -11,7 +11,6 @@
 
 #include "libslic3r.h"
 #include "Utils.hpp"
-#include "PrintConfig.hpp"
 
 namespace Slic3r
 {
@@ -19,6 +18,7 @@ namespace Slic3r
 class PrintConfig;
 class PrintObjectConfig;
 class ModelObject;
+class DynamicPrintConfig;
 
 // Parameters to guide object slicing and support generation.
 // The slicing parameters account for a raft and whether the 1st object layer is printed with a normal or a bridging flow
diff --git a/src/slic3r/CMakeLists.txt b/src/slic3r/CMakeLists.txt
index 5d47f9758..d1227f3c2 100644
--- a/src/slic3r/CMakeLists.txt
+++ b/src/slic3r/CMakeLists.txt
@@ -95,8 +95,6 @@ set(SLIC3R_GUI_SOURCES
     GUI/GUI_ObjectSettings.hpp
     GUI/GUI_ObjectLayers.cpp
     GUI/GUI_ObjectLayers.hpp
-    GUI/LambdaObjectDialog.cpp
-    GUI/LambdaObjectDialog.hpp
     GUI/MeshUtils.cpp
     GUI/MeshUtils.hpp
     GUI/Tab.cpp
diff --git a/src/slic3r/GUI/BackgroundSlicingProcess.cpp b/src/slic3r/GUI/BackgroundSlicingProcess.cpp
index 32b7b8365..c6d2323de 100644
--- a/src/slic3r/GUI/BackgroundSlicingProcess.cpp
+++ b/src/slic3r/GUI/BackgroundSlicingProcess.cpp
@@ -1,6 +1,7 @@
 #include "BackgroundSlicingProcess.hpp"
 #include "GUI_App.hpp"
 #include "GUI.hpp"
+#include "MainFrame.hpp"
 
 #include <wx/app.h>
 #include <wx/panel.h>
@@ -36,6 +37,7 @@
 #include "RemovableDriveManager.hpp"
 
 #include "slic3r/Utils/Thread.hpp"
+#include "slic3r/GUI/Plater.hpp"
 
 namespace Slic3r {
 
diff --git a/src/slic3r/GUI/BedShapeDialog.cpp b/src/slic3r/GUI/BedShapeDialog.cpp
index 4357a371a..f08b1a379 100644
--- a/src/slic3r/GUI/BedShapeDialog.cpp
+++ b/src/slic3r/GUI/BedShapeDialog.cpp
@@ -1,4 +1,6 @@
 #include "BedShapeDialog.hpp"
+#include "GUI_App.hpp"
+#include "OptionsGroup.hpp"
 
 #include <wx/wx.h> 
 #include <wx/numformatter.h>
diff --git a/src/slic3r/GUI/BedShapeDialog.hpp b/src/slic3r/GUI/BedShapeDialog.hpp
index bf12cc893..b583eca4a 100644
--- a/src/slic3r/GUI/BedShapeDialog.hpp
+++ b/src/slic3r/GUI/BedShapeDialog.hpp
@@ -3,7 +3,7 @@
 // The bed shape dialog.
 // The dialog opens from Print Settins tab->Bed Shape : Set...
 
-#include "OptionsGroup.hpp"
+#include "GUI_Utils.hpp"
 #include "2DBed.hpp"
 #include "I18N.hpp"
 
@@ -13,6 +13,8 @@
 namespace Slic3r {
 namespace GUI {
 
+class ConfigOptionsGroup;
+
 using ConfigOptionsGroupShp = std::shared_ptr<ConfigOptionsGroup>;
 class BedShapePanel : public wxPanel
 {
diff --git a/src/slic3r/GUI/ConfigWizard.cpp b/src/slic3r/GUI/ConfigWizard.cpp
index e242033d9..18d8bb312 100644
--- a/src/slic3r/GUI/ConfigWizard.cpp
+++ b/src/slic3r/GUI/ConfigWizard.cpp
@@ -27,6 +27,7 @@
 
 #include "libslic3r/Utils.hpp"
 #include "GUI.hpp"
+#include "GUI_App.hpp"
 #include "GUI_Utils.hpp"
 #include "slic3r/Config/Snapshot.hpp"
 #include "slic3r/Utils/PresetUpdater.hpp"
diff --git a/src/slic3r/GUI/ConfigWizard_private.hpp b/src/slic3r/GUI/ConfigWizard_private.hpp
index 49993bfb1..4fa9c472f 100644
--- a/src/slic3r/GUI/ConfigWizard_private.hpp
+++ b/src/slic3r/GUI/ConfigWizard_private.hpp
@@ -24,6 +24,9 @@
 #include "AppConfig.hpp"
 #include "PresetBundle.hpp"
 #include "BedShapeDialog.hpp"
+#include "GUI.hpp"
+#include "wxExtensions.hpp"
+
 
 namespace fs = boost::filesystem;
 
diff --git a/src/slic3r/GUI/DoubleSlider.cpp b/src/slic3r/GUI/DoubleSlider.cpp
index 3374863b8..45e242709 100644
--- a/src/slic3r/GUI/DoubleSlider.cpp
+++ b/src/slic3r/GUI/DoubleSlider.cpp
@@ -8,6 +8,7 @@
 #endif // ENABLE_GCODE_VIEWER
 #include "GUI.hpp"
 #include "GUI_App.hpp"
+#include "Plater.hpp"
 #include "I18N.hpp"
 #include "ExtruderSequenceDialog.hpp"
 #include "libslic3r/Print.hpp"
diff --git a/src/slic3r/GUI/Field.cpp b/src/slic3r/GUI/Field.cpp
index 4c7419cea..3a06c3056 100644
--- a/src/slic3r/GUI/Field.cpp
+++ b/src/slic3r/GUI/Field.cpp
@@ -3,6 +3,8 @@
 #include "I18N.hpp"
 #include "Field.hpp"
 #include "wxExtensions.hpp"
+#include "Plater.hpp"
+#include "MainFrame.hpp"
 
 #include "libslic3r/PrintConfig.hpp"
 
diff --git a/src/slic3r/GUI/GLCanvas3D.cpp b/src/slic3r/GUI/GLCanvas3D.cpp
index 2b12a8a61..e5dcdd776 100644
--- a/src/slic3r/GUI/GLCanvas3D.cpp
+++ b/src/slic3r/GUI/GLCanvas3D.cpp
@@ -25,6 +25,8 @@
 #include "slic3r/GUI/OpenGLManager.hpp"
 #include "slic3r/GUI/3DBed.hpp"
 #include "slic3r/GUI/Camera.hpp"
+#include "slic3r/GUI/Plater.hpp"
+#include "slic3r/GUI/MainFrame.hpp"
 
 #include "GUI_App.hpp"
 #include "GUI_ObjectList.hpp"
diff --git a/src/slic3r/GUI/GLCanvas3D.hpp b/src/slic3r/GUI/GLCanvas3D.hpp
index 6551066a9..bba87d07a 100644
--- a/src/slic3r/GUI/GLCanvas3D.hpp
+++ b/src/slic3r/GUI/GLCanvas3D.hpp
@@ -5,7 +5,6 @@
 #include <memory>
 #include <chrono>
 
-#include "3DScene.hpp"
 #include "GLToolbar.hpp"
 #include "Event.hpp"
 #include "Selection.hpp"
diff --git a/src/slic3r/GUI/GLSelectionRectangle.cpp b/src/slic3r/GUI/GLSelectionRectangle.cpp
index d1d2b89f1..d7f3f7a3a 100644
--- a/src/slic3r/GUI/GLSelectionRectangle.cpp
+++ b/src/slic3r/GUI/GLSelectionRectangle.cpp
@@ -3,6 +3,7 @@
 #include "3DScene.hpp"
 #include "GLCanvas3D.hpp"
 #include "GUI_App.hpp"
+#include "Plater.hpp"
 
 #include <GL/glew.h>
 
diff --git a/src/slic3r/GUI/GLToolbar.cpp b/src/slic3r/GUI/GLToolbar.cpp
index 603cfc3ad..59401b11a 100644
--- a/src/slic3r/GUI/GLToolbar.cpp
+++ b/src/slic3r/GUI/GLToolbar.cpp
@@ -6,6 +6,7 @@
 #include "slic3r/GUI/GLCanvas3D.hpp"
 #include "slic3r/GUI/GUI_App.hpp"
 #include "slic3r/GUI/Camera.hpp"
+#include "slic3r/GUI/Plater.hpp"
 
 #include <wx/event.h>
 #include <wx/bitmap.h>
diff --git a/src/slic3r/GUI/GUI_App.cpp b/src/slic3r/GUI/GUI_App.cpp
index 4c53a5b94..3c000f62e 100644
--- a/src/slic3r/GUI/GUI_App.cpp
+++ b/src/slic3r/GUI/GUI_App.cpp
@@ -37,6 +37,8 @@
 #include "AppConfig.hpp"
 #include "PresetBundle.hpp"
 #include "3DScene.hpp"
+#include "MainFrame.hpp"
+#include "Plater.hpp"
 
 #include "../Utils/PresetUpdater.hpp"
 #include "../Utils/PrintHost.hpp"
diff --git a/src/slic3r/GUI/GUI_App.hpp b/src/slic3r/GUI/GUI_App.hpp
index fdb10ff60..4ddaef844 100644
--- a/src/slic3r/GUI/GUI_App.hpp
+++ b/src/slic3r/GUI/GUI_App.hpp
@@ -3,8 +3,7 @@
 
 #include <memory>
 #include <string>
-#include "libslic3r/PrintConfig.hpp"
-#include "MainFrame.hpp"
+#include "Preset.hpp"
 #include "ImGuiWrapper.hpp"
 #include "ConfigWizard.hpp"
 #include "OpenGLManager.hpp"
@@ -30,11 +29,21 @@ class PresetBundle;
 class PresetUpdater;
 class ModelObject;
 class PrintHostJobQueue;
-
+class Model;
 
 namespace GUI{
 class RemovableDriveManager;
 class OtherInstanceMessageHandler;
+class MainFrame;
+class Sidebar;
+class ObjectManipulation;
+class ObjectSettings;
+class ObjectList;
+class ObjectLayers;
+class Plater;
+
+
+
 enum FileType
 {
     FT_STL,
diff --git a/src/slic3r/GUI/GUI_ObjectLayers.cpp b/src/slic3r/GUI/GUI_ObjectLayers.cpp
index cd65f69fc..b1a5512d4 100644
--- a/src/slic3r/GUI/GUI_ObjectLayers.cpp
+++ b/src/slic3r/GUI/GUI_ObjectLayers.cpp
@@ -2,9 +2,11 @@
 #include "GUI_ObjectList.hpp"
 
 #include "OptionsGroup.hpp"
+#include "GUI_App.hpp"
 #include "PresetBundle.hpp"
 #include "libslic3r/Model.hpp"
 #include "GLCanvas3D.hpp"
+#include "Plater.hpp"
 
 #include <boost/algorithm/string.hpp>
 
diff --git a/src/slic3r/GUI/GUI_ObjectList.cpp b/src/slic3r/GUI/GUI_ObjectList.cpp
index 35ec2e485..a468c9f93 100644
--- a/src/slic3r/GUI/GUI_ObjectList.cpp
+++ b/src/slic3r/GUI/GUI_ObjectList.cpp
@@ -4,13 +4,13 @@
 #include "GUI_ObjectLayers.hpp"
 #include "GUI_App.hpp"
 #include "I18N.hpp"
+#include "Plater.hpp"
 
 #include "OptionsGroup.hpp"
 #include "PresetBundle.hpp"
 #include "Tab.hpp"
 #include "wxExtensions.hpp"
 #include "libslic3r/Model.hpp"
-#include "LambdaObjectDialog.hpp"
 #include "GLCanvas3D.hpp"
 #include "Selection.hpp"
 
@@ -1781,6 +1781,22 @@ void ObjectList::append_menu_items_convert_unit(wxMenu* menu)
         [](wxCommandEvent&) { wxGetApp().plater()->convert_unit(false); }, "", menu);
 }
 
+void ObjectList::append_menu_item_merge_to_multipart_object(wxMenu* menu)
+{
+    menu->AppendSeparator();
+    append_menu_item(menu, wxID_ANY, _L("Merge"), _L("Merge objects to the one multipart object"),
+        [this](wxCommandEvent&) { merge(true); }, "", menu,
+        [this]() { return this->can_merge_to_multipart_object(); }, wxGetApp().plater());
+}
+
+void ObjectList::append_menu_item_merge_to_single_object(wxMenu* menu)
+{
+    menu->AppendSeparator();
+    append_menu_item(menu, wxID_ANY, _L("Merge"), _L("Merge objects to the one single object"),
+        [this](wxCommandEvent&) { merge(false); }, "", menu,
+        [this]() { return this->can_merge_to_single_object(); }, wxGetApp().plater());
+}
+
 void ObjectList::create_object_popupmenu(wxMenu *menu)
 {
 #ifdef __WXOSX__  
@@ -1795,6 +1811,10 @@ void ObjectList::create_object_popupmenu(wxMenu *menu)
 
     // Split object to parts
     append_menu_item_split(menu);
+//    menu->AppendSeparator();
+
+    // Merge multipart object to the single object
+//    append_menu_item_merge_to_single_object(menu);
     menu->AppendSeparator();
 
     // Layers Editing for object
@@ -2365,6 +2385,107 @@ void ObjectList::split()
     changed_object(obj_idx);
 }
 
+void ObjectList::merge(bool to_multipart_object)
+{
+    // merge selected objects to the multipart object
+    if (to_multipart_object)
+    {
+        std::vector<int> obj_idxs;
+        wxDataViewItemArray sels;
+        GetSelections(sels);
+        assert(!sels.IsEmpty());
+
+        for (wxDataViewItem item : sels) {
+            const ItemType type = m_objects_model->GetItemType(item);
+            assert(type & (itObject/* | itInstance*/));
+            obj_idxs.emplace_back(type & itObject ? m_objects_model->GetIdByItem(item) :
+                m_objects_model->GetIdByItem(m_objects_model->GetTopParent(item)));
+        }
+        std::sort(obj_idxs.begin(), obj_idxs.end());
+        obj_idxs.erase(std::unique(obj_idxs.begin(), obj_idxs.end()), obj_idxs.end());
+
+        if (obj_idxs.size() <= 1)
+            return;
+
+        Plater::TakeSnapshot snapshot(wxGetApp().plater(), _L("Merge"));
+
+        Model* model = (*m_objects)[0]->get_model();
+        ModelObject* new_object = model->add_object();
+        new_object->name = _u8L("Merged");
+        DynamicPrintConfig* new_config = &new_object->config;
+
+        const Vec3d& main_offset  = (*m_objects)[0]->instances[0]->get_offset();
+
+        for (int obj_idx : obj_idxs)
+        {
+            ModelObject* object = (*m_objects)[obj_idx];
+            Vec3d offset = object->instances[0]->get_offset();
+
+            if (object->id() == (*m_objects)[0]->id())
+                new_object->add_instance(*object->instances[0]);
+            auto new_opt_keys = new_config->keys();
+
+            const DynamicPrintConfig& from_config = object->config;
+            auto opt_keys = from_config.keys();
+
+            // merge settings
+            for (auto& opt_key : opt_keys) {
+                if (find(new_opt_keys.begin(), new_opt_keys.end(), opt_key) == new_opt_keys.end()) {
+                    const ConfigOption* option = from_config.option(opt_key);
+                    if (!option) {
+                        // if current option doesn't exist in prints.get_edited_preset(),
+                        // get it from default config values
+                        option = DynamicPrintConfig::new_from_defaults_keys({ opt_key })->option(opt_key);
+                    }
+                    new_config->set_key_value(opt_key, option->clone());
+                }
+            }
+
+            // merge volumes
+            for (const ModelVolume* volume : object->volumes) {
+                ModelVolume* new_volume = new_object->add_volume(*volume);
+                Vec3d vol_offset = offset - main_offset + new_volume->get_offset();
+                new_volume->set_offset(vol_offset);
+            }
+            // save extruder value if it was set
+            if (object->volumes.size() == 1 && find(opt_keys.begin(), opt_keys.end(), "extruder") != opt_keys.end()) {
+                ModelVolume* volume = new_object->volumes.back();
+                const ConfigOption* option = from_config.option("extruder");
+                if (option) 
+                    volume->config.set_key_value("extruder", option->clone());
+            }
+
+            // merge layers
+            for (const auto& range : object->layer_config_ranges)
+                new_object->layer_config_ranges.emplace(range);
+        }
+        // remove selected objects
+        remove();
+        // Add new object(merged) to the object_list
+        add_object_to_list(m_objects->size() - 1);
+    }
+    // merge all parts to the one single object
+    // all part's settings will be lost
+    else
+    {
+        wxDataViewItem item = GetSelection();
+        if (!item)
+            return;
+        const int obj_idx = m_objects_model->GetIdByItem(item);
+        if (obj_idx == -1)
+            return;
+
+        Plater::TakeSnapshot snapshot(wxGetApp().plater(), _L("Merge all parts to the one single object"));
+
+        ModelObject* model_object = (*m_objects)[obj_idx];
+        model_object->merge();
+
+        m_objects_model->DeleteVolumeChildren(item);
+
+        changed_object(obj_idx);
+    }
+}
+
 void ObjectList::layers_editing()
 {
     const Selection& selection = scene_selection();
@@ -2490,6 +2611,31 @@ bool ObjectList::can_split_instances()
     return selection.is_multiple_full_instance() || selection.is_single_full_instance();
 }
 
+bool ObjectList::can_merge_to_multipart_object() const
+{
+    wxDataViewItemArray sels;
+    GetSelections(sels);
+    if (sels.IsEmpty())
+        return false;
+
+    // should be selected just objects
+    for (wxDataViewItem item : sels)
+        if (!(m_objects_model->GetItemType(item) & (itObject/* | itInstance*/)))
+            return false;
+
+    return true;
+}
+
+bool ObjectList::can_merge_to_single_object() const
+{
+    int obj_idx = get_selected_obj_idx();
+    if (obj_idx < 0)
+        return false;
+
+    // selected object should be multipart
+    return (*m_objects)[obj_idx]->volumes.size() > 1;
+}
+
 // NO_PARAMETERS function call means that changed object index will be determine from Selection() 
 void ObjectList::changed_object(const int obj_idx/* = -1*/) const 
 {
@@ -4111,6 +4257,7 @@ void ObjectList::show_multi_selection_menu()
     }, wxGetApp().plater());
 
     append_menu_items_convert_unit(menu);
+    append_menu_item_merge_to_multipart_object(menu);
 
     wxGetApp().plater()->PopupMenu(menu);
 }
diff --git a/src/slic3r/GUI/GUI_ObjectList.hpp b/src/slic3r/GUI/GUI_ObjectList.hpp
index 0924d4216..4490ec5e9 100644
--- a/src/slic3r/GUI/GUI_ObjectList.hpp
+++ b/src/slic3r/GUI/GUI_ObjectList.hpp
@@ -254,6 +254,8 @@ public:
     void                append_menu_item_delete(wxMenu* menu);
     void                append_menu_item_scale_selection_to_fit_print_volume(wxMenu* menu);
     void                append_menu_items_convert_unit(wxMenu* menu);
+    void                append_menu_item_merge_to_multipart_object(wxMenu *menu);
+    void                append_menu_item_merge_to_single_object(wxMenu *menu);
     void                create_object_popupmenu(wxMenu *menu);
     void                create_sla_object_popupmenu(wxMenu*menu);
     void                create_part_popupmenu(wxMenu*menu);
@@ -277,6 +279,7 @@ public:
     void                del_layers_from_object(const int obj_idx);
     bool                del_subobject_from_object(const int obj_idx, const int idx, const int type);
     void                split();
+    void                merge(bool to_multipart_object);
     void                layers_editing();
 
     wxDataViewItem      add_layer_root_item(const wxDataViewItem obj_item);
@@ -287,6 +290,8 @@ public:
     bool                is_splittable();
     bool                selected_instances_of_same_object();
     bool                can_split_instances();
+    bool                can_merge_to_multipart_object() const;
+    bool                can_merge_to_single_object() const;
 
     wxPoint             get_mouse_position_in_control() const { return wxGetMousePosition() - this->GetScreenPosition(); }
     wxBoxSizer*         get_sizer() {return  m_sizer;}
diff --git a/src/slic3r/GUI/GUI_ObjectManipulation.cpp b/src/slic3r/GUI/GUI_ObjectManipulation.cpp
index 6a9e2ddc1..2c35fc316 100644
--- a/src/slic3r/GUI/GUI_ObjectManipulation.cpp
+++ b/src/slic3r/GUI/GUI_ObjectManipulation.cpp
@@ -4,11 +4,14 @@
 
 #include "GLCanvas3D.hpp"
 #include "OptionsGroup.hpp"
+#include "GUI_App.hpp"
 #include "wxExtensions.hpp"
 #include "PresetBundle.hpp"
 #include "libslic3r/Model.hpp"
 #include "libslic3r/Geometry.hpp"
 #include "Selection.hpp"
+#include "Plater.hpp"
+#include "MainFrame.hpp"
 
 #include <boost/algorithm/string.hpp>
 #include "slic3r/Utils/FixModelByWin10.hpp"
diff --git a/src/slic3r/GUI/GUI_ObjectSettings.cpp b/src/slic3r/GUI/GUI_ObjectSettings.cpp
index 1447e0768..ef78123a4 100644
--- a/src/slic3r/GUI/GUI_ObjectSettings.cpp
+++ b/src/slic3r/GUI/GUI_ObjectSettings.cpp
@@ -2,8 +2,10 @@
 #include "GUI_ObjectList.hpp"
 
 #include "OptionsGroup.hpp"
+#include "GUI_App.hpp"
 #include "wxExtensions.hpp"
 #include "PresetBundle.hpp"
+#include "Plater.hpp"
 #include "libslic3r/Model.hpp"
 
 #include <boost/algorithm/string.hpp>
diff --git a/src/slic3r/GUI/GUI_Preview.cpp b/src/slic3r/GUI/GUI_Preview.cpp
index ea437a215..c673292ef 100644
--- a/src/slic3r/GUI/GUI_Preview.cpp
+++ b/src/slic3r/GUI/GUI_Preview.cpp
@@ -12,6 +12,7 @@
 #include "GLCanvas3D.hpp"
 #include "PresetBundle.hpp"
 #include "DoubleSlider.hpp"
+#include "Plater.hpp"
 
 #include <wx/notebook.h>
 #include <wx/glcanvas.h>
diff --git a/src/slic3r/GUI/Gizmos/GLGizmoCut.cpp b/src/slic3r/GUI/Gizmos/GLGizmoCut.cpp
index 9382579ea..17c10f485 100644
--- a/src/slic3r/GUI/Gizmos/GLGizmoCut.cpp
+++ b/src/slic3r/GUI/Gizmos/GLGizmoCut.cpp
@@ -12,6 +12,7 @@
 #include <algorithm>
 
 #include "slic3r/GUI/GUI_App.hpp"
+#include "slic3r/GUI/Plater.hpp"
 
 
 namespace Slic3r {
diff --git a/src/slic3r/GUI/Gizmos/GLGizmoFdmSupports.cpp b/src/slic3r/GUI/Gizmos/GLGizmoFdmSupports.cpp
index e90f76fc4..97e2ffed2 100644
--- a/src/slic3r/GUI/Gizmos/GLGizmoFdmSupports.cpp
+++ b/src/slic3r/GUI/Gizmos/GLGizmoFdmSupports.cpp
@@ -8,6 +8,7 @@
 #include "slic3r/GUI/GUI_App.hpp"
 #include "slic3r/GUI/PresetBundle.hpp"
 #include "slic3r/GUI/Camera.hpp"
+#include "slic3r/GUI/Plater.hpp"
 #include "libslic3r/Model.hpp"
 
 
diff --git a/src/slic3r/GUI/Gizmos/GLGizmoSlaSupports.cpp b/src/slic3r/GUI/Gizmos/GLGizmoSlaSupports.cpp
index 712311e81..268a15df3 100644
--- a/src/slic3r/GUI/Gizmos/GLGizmoSlaSupports.cpp
+++ b/src/slic3r/GUI/Gizmos/GLGizmoSlaSupports.cpp
@@ -3,6 +3,7 @@
 #include "slic3r/GUI/GLCanvas3D.hpp"
 #include "slic3r/GUI/Camera.hpp"
 #include "slic3r/GUI/Gizmos/GLGizmosCommon.hpp"
+#include "slic3r/GUI/MainFrame.hpp"
 
 #include <GL/glew.h>
 
diff --git a/src/slic3r/GUI/Gizmos/GLGizmosCommon.cpp b/src/slic3r/GUI/Gizmos/GLGizmosCommon.cpp
index e35750fa0..9dd9c6565 100644
--- a/src/slic3r/GUI/Gizmos/GLGizmosCommon.cpp
+++ b/src/slic3r/GUI/Gizmos/GLGizmosCommon.cpp
@@ -6,6 +6,7 @@
 #include "libslic3r/SLAPrint.hpp"
 #include "slic3r/GUI/GUI_App.hpp"
 #include "slic3r/GUI/Camera.hpp"
+#include "slic3r/GUI/Plater.hpp"
 
 #include <GL/glew.h>
 
diff --git a/src/slic3r/GUI/Gizmos/GLGizmosManager.cpp b/src/slic3r/GUI/Gizmos/GLGizmosManager.cpp
index 324c50011..355927fb1 100644
--- a/src/slic3r/GUI/Gizmos/GLGizmosManager.cpp
+++ b/src/slic3r/GUI/Gizmos/GLGizmosManager.cpp
@@ -6,6 +6,7 @@
 #include "slic3r/GUI/GUI_App.hpp"
 #include "slic3r/GUI/GUI_ObjectManipulation.hpp"
 #include "slic3r/GUI/PresetBundle.hpp"
+#include "slic3r/GUI/Plater.hpp"
 #include "slic3r/Utils/UndoRedo.hpp"
 
 #include "slic3r/GUI/Gizmos/GLGizmoMove.hpp"
diff --git a/src/slic3r/GUI/InstanceCheck.cpp b/src/slic3r/GUI/InstanceCheck.cpp
index 4470876c7..d5ecbcd0f 100644
--- a/src/slic3r/GUI/InstanceCheck.cpp
+++ b/src/slic3r/GUI/InstanceCheck.cpp
@@ -1,5 +1,10 @@
 #include "GUI_App.hpp"
 #include "InstanceCheck.hpp"
+#include "Plater.hpp"
+
+#ifdef _WIN32
+  #include "MainFrame.hpp"
+#endif
 
 #include "libslic3r/Utils.hpp"
 #include "libslic3r/Config.hpp"
diff --git a/src/slic3r/GUI/LambdaObjectDialog.cpp b/src/slic3r/GUI/LambdaObjectDialog.cpp
deleted file mode 100644
index 63c8d329c..000000000
--- a/src/slic3r/GUI/LambdaObjectDialog.cpp
+++ /dev/null
@@ -1,200 +0,0 @@
-#include "LambdaObjectDialog.hpp"
-
-#include <wx/window.h>
-#include <wx/button.h>
-#include "OptionsGroup.hpp"
-#include "I18N.hpp"
-
-namespace Slic3r
-{
-namespace GUI
-{
-
-LambdaObjectDialog::LambdaObjectDialog(wxWindow* parent,
-                                       const wxString type_name):
-                                       m_type_name(type_name)
-{
-	Create(parent, wxID_ANY, _(L("Lambda Object")),
-        parent->GetScreenPosition(), wxDefaultSize,
-		wxDEFAULT_DIALOG_STYLE | wxRESIZE_BORDER);
-
-	// instead of double dim[3] = { 1.0, 1.0, 1.0 };
-	object_parameters.dim[0] = 1.0;
-	object_parameters.dim[1] = 1.0;
-	object_parameters.dim[2] = 1.0;
-
-	sizer = new wxBoxSizer(wxVERTICAL);
-
-	// modificator options
-    if (m_type_name == wxEmptyString) {
-        m_modificator_options_book = new wxChoicebook(  this, wxID_ANY, wxDefaultPosition,
-                                                        wxDefaultSize, wxCHB_TOP);
-        sizer->Add(m_modificator_options_book, 1, wxEXPAND | wxALL, 10);
-    }
-    else {
-        m_panel = new wxPanel(this, wxID_ANY, wxDefaultPosition, wxDefaultSize);
-        sizer->Add(m_panel, 1, wxEXPAND | wxALL, 10);
-    }
-
-    ConfigOptionDef def;
-    def.width = 70;
-	auto optgroup = init_modificator_options_page(_(L("Box")));
-    if (optgroup) {
-		optgroup->m_on_change = [this](t_config_option_key opt_key, boost::any value) {
-			int opt_id =	opt_key == "l" ? 0 :
-							opt_key == "w" ? 1 : 
-							opt_key == "h" ? 2 : -1;
-			if (opt_id < 0) return;
-			object_parameters.dim[opt_id] = boost::any_cast<double>(value);
-		};
-
-		def.type = coFloat;
-		def.set_default_value(new ConfigOptionFloat{ 1.0 });
-		def.label = L("Length");
-		Option option(def, "l");
-		optgroup->append_single_option_line(option);
-		
-		def.label = L("Width");
-		option = Option(def, "w");
-		optgroup->append_single_option_line(option);
-		
-		def.label = L("Height");
-		option = Option(def, "h");
-		optgroup->append_single_option_line(option);
-	}
-
-	optgroup = init_modificator_options_page(_(L("Cylinder")));
-	if (optgroup) {
-		optgroup->m_on_change = [this](t_config_option_key opt_key, boost::any value) {
-			int val = boost::any_cast<int>(value);
-			if (opt_key == "cyl_r")
-				object_parameters.cyl_r = val;
-			else if (opt_key == "cyl_h")
-				object_parameters.cyl_h = val;
-			else return;
-		};
-
-		def.type = coInt;
-		def.set_default_value(new ConfigOptionInt{ 1 });
-		def.label = L("Radius");
-		auto option = Option(def, "cyl_r");
-		optgroup->append_single_option_line(option);
-
-		def.label = L("Height");
-		option = Option(def, "cyl_h");
-		optgroup->append_single_option_line(option);
-    }
-
-	optgroup = init_modificator_options_page(_(L("Sphere")));
-	if (optgroup) {
-		optgroup->m_on_change = [this](t_config_option_key opt_key, boost::any value) {
-			if (opt_key == "sph_rho")
-				object_parameters.sph_rho = boost::any_cast<double>(value);
-			else return;
-		};
-
-		def.type = coFloat;
-		def.set_default_value(new ConfigOptionFloat{ 1.0 });
-		def.label = L("Rho");
-		auto option = Option(def, "sph_rho");
-		optgroup->append_single_option_line(option);
-	}
-
-	optgroup = init_modificator_options_page(_(L("Slab")));
-	if (optgroup) {
-		optgroup->m_on_change = [this](t_config_option_key opt_key, boost::any value) {
-			double val = boost::any_cast<double>(value);
-			if (opt_key == "slab_z")
-				object_parameters.slab_z = val;
-			else if (opt_key == "slab_h")
-				object_parameters.slab_h = val;
-			else return;
-		};
-
-		def.type = coFloat;
-		def.set_default_value(new ConfigOptionFloat{ 1.0 });
-		def.label = L("Height");
-		auto option = Option(def, "slab_h");
-		optgroup->append_single_option_line(option);
-
-		def.label = L("Initial Z");
-		option = Option(def, "slab_z");
-		optgroup->append_single_option_line(option);
-	}
-
-	Bind(wxEVT_CHOICEBOOK_PAGE_CHANGED, ([this](wxCommandEvent e)
-	{
-		auto page_idx = m_modificator_options_book->GetSelection();
-		if (page_idx < 0) return;
-		switch (page_idx)
-		{
-		case 0:
-			object_parameters.type = LambdaTypeBox;
-			break;
-		case 1:
-			object_parameters.type = LambdaTypeCylinder;
-			break;
-		case 2:
-			object_parameters.type = LambdaTypeSphere;
-			break;
-		case 3:
-			object_parameters.type = LambdaTypeSlab;
-			break;
-		default:
-			break;
-		}
-	}));
-
-	const auto button_sizer = CreateStdDialogButtonSizer(wxOK | wxCANCEL);
-
-	wxButton* btn_OK = static_cast<wxButton*>(FindWindowById(wxID_OK, this));
-	btn_OK->Bind(wxEVT_BUTTON, [this](wxCommandEvent&) {
-		// validate user input
-		if (!CanClose())return;
-		EndModal(wxID_OK);
-		Destroy();
-	});
-
-	wxButton* btn_CANCEL = static_cast<wxButton*>(FindWindowById(wxID_CANCEL, this));
-	btn_CANCEL->Bind(wxEVT_BUTTON, [this](wxCommandEvent&) {
-		// validate user input
-		if (!CanClose())return;
-		EndModal(wxID_CANCEL);
-		Destroy();
-	});
-
-	sizer->Add(button_sizer, 0, wxALIGN_CENTER_HORIZONTAL | wxBOTTOM, 10);
-
-	SetSizer(sizer);
-	sizer->Fit(this);
-	sizer->SetSizeHints(this);
-}
-
-// Called from the constructor.
-// Create a panel for a rectangular / circular / custom bed shape.
-ConfigOptionsGroupShp LambdaObjectDialog::init_modificator_options_page(const wxString& title)
-{
-    if (!m_type_name.IsEmpty() && m_type_name != title)
-        return nullptr;
-
-    auto panel = m_type_name.IsEmpty() ? new wxPanel(m_modificator_options_book) : m_panel;
-
-	ConfigOptionsGroupShp optgroup;
-	optgroup = std::make_shared<ConfigOptionsGroup>(panel, _(L("Add")) + " " +title + " " +dots);
-	optgroup->label_width = 100;
-
-	m_optgroups.push_back(optgroup);
-
-    if (m_type_name.IsEmpty()) {
-        panel->SetSizerAndFit(optgroup->sizer);
-        m_modificator_options_book->AddPage(panel, title);
-    }
-    else
-        panel->SetSizer(optgroup->sizer);
-
-    return optgroup;
-}
-
-
-} //namespace GUI
-} //namespace Slic3r 
diff --git a/src/slic3r/GUI/LambdaObjectDialog.hpp b/src/slic3r/GUI/LambdaObjectDialog.hpp
deleted file mode 100644
index 5bc2d19a5..000000000
--- a/src/slic3r/GUI/LambdaObjectDialog.hpp
+++ /dev/null
@@ -1,59 +0,0 @@
-#ifndef slic3r_LambdaObjectDialog_hpp_
-#define slic3r_LambdaObjectDialog_hpp_
-
-#include <vector>
-#include <memory>
-
-#include <wx/dialog.h>
-#include <wx/sizer.h>
-#include <wx/choicebk.h>
-
-class wxPanel;
-
-namespace Slic3r
-{
-namespace GUI
-{
-enum LambdaTypeIDs{
-    LambdaTypeBox,
-    LambdaTypeCylinder,
-    LambdaTypeSphere,
-    LambdaTypeSlab
-};
-
-struct OBJECT_PARAMETERS
-{
-    LambdaTypeIDs	type = LambdaTypeBox;
-    double			dim[3];// = { 1.0, 1.0, 1.0 };
-    int				cyl_r = 1;
-    int				cyl_h = 1;
-    double			sph_rho = 1.0;
-    double			slab_h = 1.0;
-    double			slab_z = 0.0;
-};
-class ConfigOptionsGroup;
-using ConfigOptionsGroupShp = std::shared_ptr<ConfigOptionsGroup>;
-class LambdaObjectDialog : public wxDialog
-{
-	wxChoicebook*	m_modificator_options_book = nullptr;
-	std::vector <ConfigOptionsGroupShp>	m_optgroups;
-    wxString        m_type_name;
-    wxPanel*        m_panel = nullptr;
-public:
-    LambdaObjectDialog(wxWindow* parent, 
-                       const wxString type_name = wxEmptyString);
-	~LambdaObjectDialog() {}
-
-	bool CanClose() { return true; }	// ???
-	OBJECT_PARAMETERS& ObjectParameters() { return object_parameters; }
-
-	ConfigOptionsGroupShp init_modificator_options_page(const wxString& title);
-	
-	// Note whether the window was already closed, so a pending update is not executed.
-	bool m_already_closed = false;
-	OBJECT_PARAMETERS object_parameters;
-	wxBoxSizer* sizer = nullptr;
-};
-} //namespace GUI
-} //namespace Slic3r 
-#endif  //slic3r_LambdaObjectDialog_hpp_
diff --git a/src/slic3r/GUI/MainFrame.cpp b/src/slic3r/GUI/MainFrame.cpp
index 20b713bca..d8a799eb2 100644
--- a/src/slic3r/GUI/MainFrame.cpp
+++ b/src/slic3r/GUI/MainFrame.cpp
@@ -29,6 +29,7 @@
 #include "InstanceCheck.hpp"
 #include "I18N.hpp"
 #include "GLCanvas3D.hpp"
+#include "Plater.hpp"
 
 #include <fstream>
 #include "GUI_App.hpp"
diff --git a/src/slic3r/GUI/MainFrame.hpp b/src/slic3r/GUI/MainFrame.hpp
index 43375d344..3b64be9bc 100644
--- a/src/slic3r/GUI/MainFrame.hpp
+++ b/src/slic3r/GUI/MainFrame.hpp
@@ -12,7 +12,6 @@
 #include <map>
 
 #include "GUI_Utils.hpp"
-#include "Plater.hpp"
 #include "Event.hpp"
 
 class wxNotebook;
@@ -27,6 +26,8 @@ namespace GUI
 
 class Tab;
 class PrintHostQueueDialog;
+class Plater;
+class MainFrame;
 
 enum QuickSlice
 {
diff --git a/src/slic3r/GUI/Mouse3DController.cpp b/src/slic3r/GUI/Mouse3DController.cpp
index 8f80f6847..baa9356b6 100644
--- a/src/slic3r/GUI/Mouse3DController.cpp
+++ b/src/slic3r/GUI/Mouse3DController.cpp
@@ -6,6 +6,7 @@
 #include "PresetBundle.hpp"
 #include "AppConfig.hpp"
 #include "GLCanvas3D.hpp"
+#include "Plater.hpp"
 
 #include <wx/glcanvas.h>
 
diff --git a/src/slic3r/GUI/OptionsGroup.cpp b/src/slic3r/GUI/OptionsGroup.cpp
index fa94e6321..819c214a8 100644
--- a/src/slic3r/GUI/OptionsGroup.cpp
+++ b/src/slic3r/GUI/OptionsGroup.cpp
@@ -1,5 +1,7 @@
 #include "OptionsGroup.hpp"
 #include "ConfigExceptions.hpp"
+#include "Plater.hpp"
+#include "GUI_App.hpp"
 
 #include <utility>
 #include <wx/numformatter.h>
@@ -100,6 +102,36 @@ const t_field& OptionsGroup::build_field(const t_config_option_key& id, const Co
     return field;
 }
 
+OptionsGroup::OptionsGroup(	wxWindow* _parent, const wxString& title,
+                            bool is_tab_opt /* = false */,
+                            column_t extra_clmn /* = nullptr */) :
+                m_parent(_parent), title(title),
+                m_show_modified_btns(is_tab_opt),
+                staticbox(title!=""), extra_column(extra_clmn)
+{
+    if (staticbox) {
+        stb = new wxStaticBox(_parent, wxID_ANY, _(title));
+        if (!wxOSX) stb->SetBackgroundStyle(wxBG_STYLE_PAINT);
+        stb->SetFont(wxOSX ? wxGetApp().normal_font() : wxGetApp().bold_font());
+    } else
+        stb = nullptr;
+    sizer = (staticbox ? new wxStaticBoxSizer(stb, wxVERTICAL) : new wxBoxSizer(wxVERTICAL));
+    auto num_columns = 1U;
+    if (label_width != 0) num_columns++;
+    if (extra_column != nullptr) num_columns++;
+    m_grid_sizer = new wxFlexGridSizer(0, num_columns, 1,0);
+    static_cast<wxFlexGridSizer*>(m_grid_sizer)->SetFlexibleDirection(wxBOTH/*wxHORIZONTAL*/);
+    static_cast<wxFlexGridSizer*>(m_grid_sizer)->AddGrowableCol(label_width == 0 ? 0 : !extra_column ? 1 : 2 );
+#if 0//#ifdef __WXGTK__
+    m_panel = new wxPanel( _parent, wxID_ANY, wxDefaultPosition, wxDefaultSize, wxTAB_TRAVERSAL );
+    sizer->Fit(m_panel);
+    sizer->Add(m_panel, 0, wxEXPAND | wxALL, wxOSX||!staticbox ? 0: 5);
+#else
+    sizer->Add(m_grid_sizer, 0, wxEXPAND | wxALL, wxOSX||!staticbox ? 0: 5);
+#endif /* __WXGTK__ */
+
+}
+
 void OptionsGroup::add_undo_buttuns_to_sizer(wxSizer* sizer, const t_field& field)
 {
 	if (!m_show_modified_btns) {
diff --git a/src/slic3r/GUI/OptionsGroup.hpp b/src/slic3r/GUI/OptionsGroup.hpp
index 9fbb28339..2e6f9aa0f 100644
--- a/src/slic3r/GUI/OptionsGroup.hpp
+++ b/src/slic3r/GUI/OptionsGroup.hpp
@@ -11,7 +11,6 @@
 #include "libslic3r/PrintConfig.hpp"
 
 #include "Field.hpp"
-#include "GUI_App.hpp"
 #include "I18N.hpp"
 
 // Translate the ifdef 
@@ -171,32 +170,7 @@ public:
     }
 
 	OptionsGroup(	wxWindow* _parent, const wxString& title, bool is_tab_opt = false, 
-					column_t extra_clmn = nullptr) :
-					m_parent(_parent), title(title), 
-                    m_show_modified_btns(is_tab_opt),
-					staticbox(title!=""), extra_column(extra_clmn) {
-        if (staticbox) {
-            stb = new wxStaticBox(_parent, wxID_ANY, _(title));
-            if (!wxOSX) stb->SetBackgroundStyle(wxBG_STYLE_PAINT);
-            stb->SetFont(wxOSX ? wxGetApp().normal_font() : wxGetApp().bold_font());
-        } else
-        	stb = nullptr;
-        sizer = (staticbox ? new wxStaticBoxSizer(stb, wxVERTICAL) : new wxBoxSizer(wxVERTICAL));
-        auto num_columns = 1U;
-        if (label_width != 0) num_columns++;
-        if (extra_column != nullptr) num_columns++;
-        m_grid_sizer = new wxFlexGridSizer(0, num_columns, 1,0);
-        static_cast<wxFlexGridSizer*>(m_grid_sizer)->SetFlexibleDirection(wxBOTH/*wxHORIZONTAL*/);
-        static_cast<wxFlexGridSizer*>(m_grid_sizer)->AddGrowableCol(label_width == 0 ? 0 : !extra_column ? 1 : 2 );
-#if 0//#ifdef __WXGTK__
-        m_panel = new wxPanel( _parent, wxID_ANY, wxDefaultPosition, wxDefaultSize, wxTAB_TRAVERSAL );
-        sizer->Fit(m_panel);
-        sizer->Add(m_panel, 0, wxEXPAND | wxALL, wxOSX||!staticbox ? 0: 5);
-#else
-        sizer->Add(m_grid_sizer, 0, wxEXPAND | wxALL, wxOSX||!staticbox ? 0: 5);
-#endif /* __WXGTK__ */
-
-    }
+                    column_t extra_clmn = nullptr);
 
     wxGridSizer*        get_grid_sizer() { return m_grid_sizer; }
 
diff --git a/src/slic3r/GUI/Plater.cpp b/src/slic3r/GUI/Plater.cpp
index 9286580b1..a7e029636 100644
--- a/src/slic3r/GUI/Plater.cpp
+++ b/src/slic3r/GUI/Plater.cpp
@@ -2320,9 +2320,9 @@ std::vector<size_t> Plater::priv::load_files(const std::vector<fs::path>& input_
             if (imperial_units)
                 convert_from_imperial_units(model);
             else if (model.looks_like_imperial_units()) {
-                wxMessageDialog msg_dlg(q, _L(
-                    "This model looks like saved in inches.\n"
-                    "Should I consider this model as a saved in inches and convert it?") + "\n",
+                wxMessageDialog msg_dlg(q, format_wxstr(_L(
+                    "Some object(s) in file %s looks like saved in inches.\n"
+                    "Should I consider them as a saved in inches and convert them?"), from_path(filename)) + "\n",
                     _L("Saved in inches object detected"), wxICON_WARNING | wxYES | wxNO);
                 if (msg_dlg.ShowModal() == wxID_YES)
                     convert_from_imperial_units(model);
diff --git a/src/slic3r/GUI/Preferences.cpp b/src/slic3r/GUI/Preferences.cpp
index bb189cf26..35f2ee429 100644
--- a/src/slic3r/GUI/Preferences.cpp
+++ b/src/slic3r/GUI/Preferences.cpp
@@ -1,6 +1,7 @@
 #include "Preferences.hpp"
 #include "AppConfig.hpp"
 #include "OptionsGroup.hpp"
+#include "GUI_App.hpp"
 #include "I18N.hpp"
 
 namespace Slic3r {
@@ -364,4 +365,4 @@ void PreferencesDialog::create_settings_mode_widget()
 
 
 } // GUI
-} // Slic3r
\ No newline at end of file
+} // Slic3r
diff --git a/src/slic3r/GUI/Search.cpp b/src/slic3r/GUI/Search.cpp
index a94b776a1..968589985 100644
--- a/src/slic3r/GUI/Search.cpp
+++ b/src/slic3r/GUI/Search.cpp
@@ -10,6 +10,7 @@
 
 #include "libslic3r/PrintConfig.hpp"
 #include "GUI_App.hpp"
+#include "Plater.hpp"
 #include "Tab.hpp"
 #include "PresetBundle.hpp"
 
diff --git a/src/slic3r/GUI/Search.hpp b/src/slic3r/GUI/Search.hpp
index 45a96034a..9701e6808 100644
--- a/src/slic3r/GUI/Search.hpp
+++ b/src/slic3r/GUI/Search.hpp
@@ -228,11 +228,11 @@ public:
 
     // implementation of base class virtuals to define model
 
-    virtual unsigned int GetColumnCount() const wxOVERRIDE { return colMax; }
-    virtual wxString GetColumnType(unsigned int col) const wxOVERRIDE;
-    virtual void GetValueByRow(wxVariant& variant, unsigned int row, unsigned int col) const wxOVERRIDE;
-    virtual bool GetAttrByRow(unsigned int row, unsigned int col, wxDataViewItemAttr& attr) const wxOVERRIDE { return true; }
-    virtual bool SetValueByRow(const wxVariant& variant, unsigned int row, unsigned int col) wxOVERRIDE { return false; }
+    virtual unsigned int GetColumnCount() const override { return colMax; }
+    virtual wxString GetColumnType(unsigned int col) const override;
+    virtual void GetValueByRow(wxVariant& variant, unsigned int row, unsigned int col) const override;
+    virtual bool GetAttrByRow(unsigned int row, unsigned int col, wxDataViewItemAttr& attr) const override { return true; }
+    virtual bool SetValueByRow(const wxVariant& variant, unsigned int row, unsigned int col) override { return false; }
 };
 
 
diff --git a/src/slic3r/GUI/Selection.cpp b/src/slic3r/GUI/Selection.cpp
index 682d9e2b9..add09a59d 100644
--- a/src/slic3r/GUI/Selection.cpp
+++ b/src/slic3r/GUI/Selection.cpp
@@ -9,6 +9,7 @@
 #include "GUI_ObjectList.hpp"
 #include "Gizmos/GLGizmoBase.hpp"
 #include "Camera.hpp"
+#include "Plater.hpp"
 
 #include "libslic3r/Model.hpp"
 
diff --git a/src/slic3r/GUI/SysInfoDialog.cpp b/src/slic3r/GUI/SysInfoDialog.cpp
index 74b94e1eb..3bd0fcf9f 100644
--- a/src/slic3r/GUI/SysInfoDialog.cpp
+++ b/src/slic3r/GUI/SysInfoDialog.cpp
@@ -3,6 +3,7 @@
 #include "3DScene.hpp"
 #include "GUI.hpp"
 #include "../Utils/UndoRedo.hpp"
+#include "Plater.hpp"
 
 #include <string>
 
diff --git a/src/slic3r/GUI/Tab.cpp b/src/slic3r/GUI/Tab.cpp
index 3b78b2c9a..dd412a0de 100644
--- a/src/slic3r/GUI/Tab.cpp
+++ b/src/slic3r/GUI/Tab.cpp
@@ -32,6 +32,8 @@
 #include "GUI_App.hpp"
 #include "GUI_ObjectList.hpp"
 #include "ConfigWizard.hpp"
+#include "Plater.hpp"
+#include "MainFrame.hpp"
 #include "format.hpp"
 
 namespace Slic3r {
@@ -3582,6 +3584,18 @@ void Tab::set_tooltips_text()
                                 "Click to reset current value to the last saved preset."));
 }
 
+Page::Page(wxWindow* parent, const wxString& title, const int iconID, const std::vector<ScalableBitmap>& mode_bmp_cache) :
+        m_parent(parent),
+        m_title(title),
+        m_iconID(iconID),
+        m_mode_bitmap_cache(mode_bmp_cache)
+{
+    Create(m_parent, wxID_ANY, wxDefaultPosition, wxDefaultSize, wxTAB_TRAVERSAL);
+    m_vsizer = new wxBoxSizer(wxVERTICAL);
+    m_item_color = &wxGetApp().get_label_clr_default();
+    SetSizer(m_vsizer);
+}
+
 void Page::reload_config()
 {
     for (auto group : m_optgroups)
diff --git a/src/slic3r/GUI/Tab.hpp b/src/slic3r/GUI/Tab.hpp
index 36b4a61ea..5805809bf 100644
--- a/src/slic3r/GUI/Tab.hpp
+++ b/src/slic3r/GUI/Tab.hpp
@@ -33,11 +33,12 @@
 #include "Event.hpp"
 #include "wxExtensions.hpp"
 #include "ConfigManipulation.hpp"
+#include "Preset.hpp"
+#include "OptionsGroup.hpp"
 
 namespace Slic3r {
 namespace GUI {
 
-
 // Single Tab page containing a{ vsizer } of{ optgroups }
 // package Slic3r::GUI::Tab::Page;
 using ConfigOptionsGroupShp = std::shared_ptr<ConfigOptionsGroup>;
@@ -49,17 +50,8 @@ class Page : public wxScrolledWindow
 	wxBoxSizer*		m_vsizer;
     bool            m_show = true;
 public:
-    Page(wxWindow* parent, const wxString& title, const int iconID, const std::vector<ScalableBitmap>& mode_bmp_cache) :
-			m_parent(parent),
-			m_title(title),
-			m_iconID(iconID),
-            m_mode_bitmap_cache(mode_bmp_cache)
-	{
-		Create(m_parent, wxID_ANY, wxDefaultPosition, wxDefaultSize, wxTAB_TRAVERSAL);
-		m_vsizer = new wxBoxSizer(wxVERTICAL);
-        m_item_color = &wxGetApp().get_label_clr_default();
-		SetSizer(m_vsizer);
-	}
+    Page(wxWindow* parent, const wxString& title, const int iconID,
+         const std::vector<ScalableBitmap>& mode_bmp_cache);
 	~Page() {}
 
 	bool				m_is_modified_values{ false };
diff --git a/src/slic3r/GUI/wxExtensions.cpp b/src/slic3r/GUI/wxExtensions.cpp
index 7dadffb5b..74d790df8 100644
--- a/src/slic3r/GUI/wxExtensions.cpp
+++ b/src/slic3r/GUI/wxExtensions.cpp
@@ -13,6 +13,7 @@
 #include "GUI_ObjectList.hpp"
 #include "I18N.hpp"
 #include "GUI_Utils.hpp"
+#include "Plater.hpp"
 #include "../Utils/MacDarkMode.hpp"
 
 #ifndef __WXGTK__// msw_menuitem_bitmaps is used for MSW and OSX
diff --git a/src/slic3r/Utils/PresetUpdater.cpp b/src/slic3r/Utils/PresetUpdater.cpp
index b86775c88..c32613c46 100644
--- a/src/slic3r/Utils/PresetUpdater.cpp
+++ b/src/slic3r/Utils/PresetUpdater.cpp
@@ -25,6 +25,7 @@
 #include "slic3r/GUI/UpdateDialogs.hpp"
 #include "slic3r/GUI/ConfigWizard.hpp"
 #include "slic3r/GUI/GUI_App.hpp"
+#include "slic3r/GUI/Plater.hpp"
 #include "slic3r/GUI/format.hpp"
 #include "slic3r/Utils/Http.hpp"
 #include "slic3r/Config/Version.hpp"