diff --git a/src/libslic3r/Model.cpp b/src/libslic3r/Model.cpp
index 9f0d515b3..780c4d41a 100644
--- a/src/libslic3r/Model.cpp
+++ b/src/libslic3r/Model.cpp
@@ -993,6 +993,56 @@ void ModelObject::scale_mesh_after_creation(const Vec3d &versor)
     this->invalidate_bounding_box();
 }
 
+void ModelObject::convert_units(ModelObjectPtrs& new_objects, bool from_imperial, std::vector<int> volume_idxs)
+{
+    BOOST_LOG_TRIVIAL(trace) << "ModelObject::convert_units - start";
+
+    ModelObject* new_object = new_clone(*this);
+
+    double koef = from_imperial ? 25.4 : 0.0393700787;
+    const Vec3d versor = Vec3d(koef, koef, koef);
+
+    new_object->set_model(nullptr);
+    new_object->sla_support_points.clear();
+    new_object->sla_drain_holes.clear();
+    new_object->sla_points_status = sla::PointsStatus::NoPoints;
+    new_object->clear_volumes();
+    new_object->input_file.clear();
+
+    int vol_idx = 0;
+    for (ModelVolume* volume : volumes)
+    {
+        volume->m_supported_facets.clear();
+        if (!volume->mesh().empty()) {
+            TriangleMesh mesh(volume->mesh());
+            mesh.require_shared_vertices();
+
+            ModelVolume* vol = new_object->add_volume(mesh);
+            vol->name = volume->name;
+            // Don't copy the config's ID.
+            static_cast<DynamicPrintConfig&>(vol->config) = static_cast<const DynamicPrintConfig&>(volume->config);
+            assert(vol->config.id().valid());
+            assert(vol->config.id() != volume->config.id());
+            vol->set_material(volume->material_id(), *volume->material());
+
+            // Perform conversion
+            if (volume_idxs.empty() || 
+                std::find(volume_idxs.begin(), volume_idxs.end(), vol_idx) != volume_idxs.end()) {
+                vol->scale_geometry_after_creation(versor);
+                vol->set_offset(versor.cwiseProduct(vol->get_offset()));
+            }
+            else
+                vol->set_offset(volume->get_offset());
+        }
+        vol_idx ++;
+    }
+    new_object->invalidate_bounding_box();
+
+    new_objects.push_back(new_object);
+
+    BOOST_LOG_TRIVIAL(trace) << "ModelObject::convert_units - end";
+}
+
 size_t ModelObject::materials_count() const
 {
     std::set<t_model_material_id> material_ids;
diff --git a/src/libslic3r/Model.hpp b/src/libslic3r/Model.hpp
index 07bd86aea..e3a136e11 100644
--- a/src/libslic3r/Model.hpp
+++ b/src/libslic3r/Model.hpp
@@ -281,6 +281,7 @@ public:
 
     // This method could only be called before the meshes of this ModelVolumes are not shared!
     void scale_mesh_after_creation(const Vec3d& versor);
+    void convert_units(ModelObjectPtrs&new_objects, bool from_imperial, std::vector<int> volume_idxs);
 
     size_t materials_count() const;
     size_t facets_count() const;
diff --git a/src/slic3r/GUI/3DBed.cpp b/src/slic3r/GUI/3DBed.cpp
index 73162645f..3fdcdd6fa 100644
--- a/src/slic3r/GUI/3DBed.cpp
+++ b/src/slic3r/GUI/3DBed.cpp
@@ -196,15 +196,18 @@ void Bed3D::Axes::render() const
     shader->start_using();
 
     // x axis
-    shader->set_uniform("uniform_color", { 0.75f, 0.0f, 0.0f, 1.0f });
+    std::array<float, 4> color = { 0.75f, 0.0f, 0.0f, 1.0f };
+    shader->set_uniform("uniform_color", color);
     render_axis(Geometry::assemble_transform(m_origin, { 0.0, 0.5 * M_PI, 0.0f }).cast<float>());
 
     // y axis
-    shader->set_uniform("uniform_color", { 0.0f, 0.75f, 0.0f, 1.0f });
+    color = { 0.0f, 0.75f, 0.0f, 1.0f };
+    shader->set_uniform("uniform_color", color);
     render_axis(Geometry::assemble_transform(m_origin, { -0.5 * M_PI, 0.0, 0.0f }).cast<float>());
 
     // z axis
-    shader->set_uniform("uniform_color", { 0.0f, 0.0f, 0.75f, 1.0f });
+    color = { 0.0f, 0.0f, 0.75f, 1.0f };
+    shader->set_uniform("uniform_color", color);
     render_axis(Geometry::assemble_transform(m_origin).cast<float>());
 
     shader->stop_using();
@@ -676,9 +679,19 @@ void Bed3D::render_model() const
 
     if (!m_model.get_filename().empty())
     {
+#if ENABLE_SHADERS_MANAGER
+        GLShaderProgram* shader = wxGetApp().get_shader("gouraud_light");
+        if (shader != nullptr)
+        {
+            shader->start_using();
+            m_model.render();
+            shader->stop_using();
+        }
+#else
         glsafe(::glEnable(GL_LIGHTING));
         m_model.render();
         glsafe(::glDisable(GL_LIGHTING));
+#endif // ENABLE_SHADERS_MANAGER
     }
 }
 
diff --git a/src/slic3r/GUI/3DScene.cpp b/src/slic3r/GUI/3DScene.cpp
index 29a4b84a3..6e42e52a2 100644
--- a/src/slic3r/GUI/3DScene.cpp
+++ b/src/slic3r/GUI/3DScene.cpp
@@ -1,6 +1,10 @@
 #include <GL/glew.h>
 
 #include "3DScene.hpp"
+#if ENABLE_SHADERS_MANAGER
+#include "GLShader.hpp"
+#include "GUI_App.hpp"
+#endif // ENABLE_SHADERS_MANAGER
 
 #include "libslic3r/ExtrusionEntity.hpp"
 #include "libslic3r/ExtrusionEntityCollection.hpp"
@@ -640,6 +644,12 @@ GLVolumeWithIdAndZList volumes_to_render(const GLVolumePtrs& volumes, GLVolumeCo
 
 void GLVolumeCollection::render(GLVolumeCollection::ERenderType type, bool disable_cullface, const Transform3d& view_matrix, std::function<bool(const GLVolume&)> filter_func) const
 {
+#if ENABLE_SHADERS_MANAGER
+    GLShaderProgram* shader = GUI::wxGetApp().get_current_shader();
+    if (shader == nullptr)
+        return;
+#endif // ENABLE_SHADERS_MANAGER
+
     glsafe(::glEnable(GL_BLEND));
     glsafe(::glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA));
 
@@ -650,6 +660,15 @@ void GLVolumeCollection::render(GLVolumeCollection::ERenderType type, bool disab
     glsafe(::glEnableClientState(GL_VERTEX_ARRAY));
     glsafe(::glEnableClientState(GL_NORMAL_ARRAY));
  
+#if ENABLE_SHADERS_MANAGER
+    shader->set_uniform("print_box.min", m_print_box_min, 3);
+    shader->set_uniform("print_box.max", m_print_box_max, 3);
+    shader->set_uniform("z_range", m_z_range, 2);
+    shader->set_uniform("clipping_plane", m_clipping_plane, 4);
+#if ENABLE_SLOPE_RENDERING
+    shader->set_uniform("slope.z_range", m_slope.z_range);
+#endif // ENABLE_SLOPE_RENDERING
+#else
     GLint current_program_id;
     glsafe(::glGetIntegerv(GL_CURRENT_PROGRAM, &current_program_id));
     GLint color_id = (current_program_id > 0) ? ::glGetUniformLocation(current_program_id, "uniform_color") : -1;
@@ -684,11 +703,19 @@ void GLVolumeCollection::render(GLVolumeCollection::ERenderType type, bool disab
     if (slope_z_range_id != -1)
         glsafe(::glUniform2fv(slope_z_range_id, 1, (const GLfloat*)m_slope.z_range.data()));
 #endif // ENABLE_SLOPE_RENDERING
+#endif // ENABLE_SHADERS_MANAGER
 
     GLVolumeWithIdAndZList to_render = volumes_to_render(this->volumes, type, view_matrix, filter_func);
     for (GLVolumeWithIdAndZ& volume : to_render) {
         volume.first->set_render_color();
 #if ENABLE_SLOPE_RENDERING
+#if ENABLE_SHADERS_MANAGER
+        shader->set_uniform("uniform_color", volume.first->render_color, 4);
+        shader->set_uniform("print_box.actived", volume.first->shader_outside_printer_detection_enabled);
+        shader->set_uniform("print_box.volume_world_matrix", volume.first->world_matrix());
+        shader->set_uniform("slope.actived", m_slope.active && !volume.first->is_modifier && !volume.first->is_wipe_tower);
+        shader->set_uniform("slope.volume_world_normal_matrix", volume.first->world_matrix().matrix().block(0, 0, 3, 3).inverse().transpose().cast<float>());
+#else
         if (color_id >= 0)
             glsafe(::glUniform4fv(color_id, 1, (const GLfloat*)volume.first->render_color));
         else
@@ -708,6 +735,7 @@ void GLVolumeCollection::render(GLVolumeCollection::ERenderType type, bool disab
             Matrix3f normal_matrix = volume.first->world_matrix().matrix().block(0, 0, 3, 3).inverse().transpose().cast<float>();
             glsafe(::glUniformMatrix3fv(slope_normal_matrix_id, 1, GL_FALSE, (const GLfloat*)normal_matrix.data()));
         }
+#endif // ENABLE_SHADERS_MANAGER
 
         volume.first->render();
 #else
@@ -1912,6 +1940,12 @@ void GLModel::reset()
 
 void GLModel::render() const
 {
+#if ENABLE_SHADERS_MANAGER
+    GLShaderProgram* shader = GUI::wxGetApp().get_current_shader();
+    if (shader == nullptr)
+        return;
+#endif // ENABLE_SHADERS_MANAGER
+
     glsafe(::glEnable(GL_BLEND));
     glsafe(::glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA));
 
@@ -1919,16 +1953,22 @@ void GLModel::render() const
     glsafe(::glEnableClientState(GL_VERTEX_ARRAY));
     glsafe(::glEnableClientState(GL_NORMAL_ARRAY));
 
+#if !ENABLE_SHADERS_MANAGER
     GLint current_program_id;
     glsafe(::glGetIntegerv(GL_CURRENT_PROGRAM, &current_program_id));
     GLint color_id = (current_program_id > 0) ? ::glGetUniformLocation(current_program_id, "uniform_color") : -1;
     glcheck();
+#endif // !ENABLE_SHADERS_MANAGER
 
 #if ENABLE_SLOPE_RENDERING
+#if ENABLE_SHADERS_MANAGER
+    shader->set_uniform("uniform_color", m_volume.render_color, 4);
+#else
     if (color_id >= 0)
         glsafe(::glUniform4fv(color_id, 1, (const GLfloat*)m_volume.render_color));
     else
         glsafe(::glColor4fv(m_volume.render_color));
+#endif // ENABLE_SHADERS_MANAGER
 
     m_volume.render();
 #else
diff --git a/src/slic3r/GUI/3DScene.hpp b/src/slic3r/GUI/3DScene.hpp
index 86072754d..fd74cd491 100644
--- a/src/slic3r/GUI/3DScene.hpp
+++ b/src/slic3r/GUI/3DScene.hpp
@@ -26,12 +26,6 @@ inline void glAssertRecentCall() { }
 #endif
 
 namespace Slic3r {
-namespace GUI {
-class Bed3D;
-struct Camera;
-class GLToolbar;
-} // namespace GUI
-
 class SLAPrintObject;
 enum  SLAPrintObjectStep : unsigned int;
 class DynamicPrintConfig;
diff --git a/src/slic3r/GUI/GLCanvas3D.cpp b/src/slic3r/GUI/GLCanvas3D.cpp
index 51079c892..5f9325b14 100644
--- a/src/slic3r/GUI/GLCanvas3D.cpp
+++ b/src/slic3r/GUI/GLCanvas3D.cpp
@@ -490,16 +490,16 @@ void GLCanvas3D::LayersEditing::render_volumes(const GLCanvas3D& canvas, const G
     assert(this->last_object_id != -1);
 #if ENABLE_SHADERS_MANAGER
     GLShaderProgram* shader = wxGetApp().get_shader("variable_layer_height");
-    assert(shader != nullptr);
+    if (shader == nullptr)
+        return;
 
-    GLint current_program_id = 0;
-    glsafe(::glGetIntegerv(GL_CURRENT_PROGRAM, &current_program_id));
-    if (shader->get_id() != static_cast<GLuint>(current_program_id))
+    GLShaderProgram* current_shader = wxGetApp().get_current_shader();
+    if (shader->get_id() != current_shader->get_id())
         // The layer editing shader is not yet active. Activate it.
         shader->start_using();
     else
         // The layer editing shader was already active.
-        current_program_id = 0;
+        current_shader = nullptr;
 
     const_cast<LayersEditing*>(this)->generate_layer_height_texture();
 
@@ -529,7 +529,6 @@ void GLCanvas3D::LayersEditing::render_volumes(const GLCanvas3D& canvas, const G
     GLint object_max_z_id = ::glGetUniformLocation(shader_id, "object_max_z");
     glcheck();
 
-
     if (z_to_texture_row_id != -1 && z_texture_row_to_normalized_id != -1 && z_cursor_id != -1 && z_cursor_band_width_id != -1 && world_matrix_id != -1)
     {
         const_cast<LayersEditing*>(this)->generate_layer_height_texture();
@@ -568,9 +567,12 @@ void GLCanvas3D::LayersEditing::render_volumes(const GLCanvas3D& canvas, const G
         }
         // Revert back to the previous shader.
         glBindTexture(GL_TEXTURE_2D, 0);
+#if ENABLE_SHADERS_MANAGER
+        if (current_shader != nullptr)
+            current_shader->start_using();
+#else
         if (current_program_id > 0)
             glsafe(::glUseProgram(current_program_id));
-#if !ENABLE_SHADERS_MANAGER
     }
     else 
     {
@@ -584,7 +586,7 @@ void GLCanvas3D::LayersEditing::render_volumes(const GLCanvas3D& canvas, const G
 			glvolume->render();
 		}
 	}
-#endif // !ENABLE_SHADERS_MANAGER
+#endif // ENABLE_SHADERS_MANAGER
 }
 
 void GLCanvas3D::LayersEditing::adjust_layer_height_profile()
@@ -5721,7 +5723,7 @@ void GLCanvas3D::_check_and_update_toolbar_icon_scale() const
 
     // set minimum scale as a auto scale for the toolbars
     float new_scale = std::min(new_h_scale, new_v_scale);
-    if (fabs(new_scale - scale) > EPSILON)
+    if (fabs(new_scale - scale) > 0.01) // scale is changed by 1% and more
         wxGetApp().set_auto_toolbar_icon_scale(new_scale);
 }
 
diff --git a/src/slic3r/GUI/GLShader.cpp b/src/slic3r/GUI/GLShader.cpp
index 7aa2aff08..d0b926794 100644
--- a/src/slic3r/GUI/GLShader.cpp
+++ b/src/slic3r/GUI/GLShader.cpp
@@ -6,6 +6,7 @@
 
 #include <boost/nowide/fstream.hpp>
 #include <GL/glew.h>
+#include <cassert>
 
 #if ENABLE_SHADERS_MANAGER
 #include <boost/log/trivial.hpp>
@@ -23,8 +24,7 @@ bool GLShaderProgram::init_from_files(const std::string& name, const ShaderFilen
     auto load_from_file = [](const std::string& filename) {
         std::string path = resources_dir() + "/shaders/" + filename;
         boost::nowide::ifstream s(path, boost::nowide::ifstream::binary);
-        if (!s.good())
-        {
+        if (!s.good()) {
             BOOST_LOG_TRIVIAL(error) << "Couldn't open file: '" << path << "'";
             return std::string();
         }
@@ -34,8 +34,7 @@ bool GLShaderProgram::init_from_files(const std::string& name, const ShaderFilen
         s.seekg(0, s.beg);
         std::string source(file_length, '\0');
         s.read(source.data(), file_length);
-        if (!s.good())
-        {
+        if (!s.good()) {
             BOOST_LOG_TRIVIAL(error) << "Error while loading file: '" << path << "'";
             return std::string();
         }
@@ -49,8 +48,9 @@ bool GLShaderProgram::init_from_files(const std::string& name, const ShaderFilen
         sources[i] = filenames[i].empty() ? std::string() : load_from_file(filenames[i]);
     }
 
-    bool valid = (!sources[static_cast<size_t>(EShaderType::Vertex)].empty() && !sources[static_cast<size_t>(EShaderType::Fragment)].empty()) ||
-        !sources[static_cast<size_t>(EShaderType::Compute)].empty();
+    bool valid = !sources[static_cast<size_t>(EShaderType::Vertex)].empty() && !sources[static_cast<size_t>(EShaderType::Fragment)].empty() && sources[static_cast<size_t>(EShaderType::Compute)].empty();
+    valid |= !sources[static_cast<size_t>(EShaderType::Compute)].empty() && sources[static_cast<size_t>(EShaderType::Vertex)].empty() && sources[static_cast<size_t>(EShaderType::Fragment)].empty() && 
+              sources[static_cast<size_t>(EShaderType::Geometry)].empty() && sources[static_cast<size_t>(EShaderType::TessEvaluation)].empty() && sources[static_cast<size_t>(EShaderType::TessControl)].empty();
 
     return valid ? init_from_texts(name, sources) : false;
 }
@@ -107,9 +107,11 @@ bool GLShaderProgram::init_from_texts(const std::string& name, const ShaderSourc
             auto [result, id] = create_shader(type);
             if (result)
                 shader_ids[i] = id;
-            else
-            {
+            else {
                 BOOST_LOG_TRIVIAL(error) << "glCreateShader() failed for " << shader_type_as_string(type) << " shader of shader program '" << name << "'";
+
+                // release shaders
+                release_shaders(shader_ids);
                 return false;
             }
 
@@ -125,7 +127,7 @@ bool GLShaderProgram::init_from_texts(const std::string& name, const ShaderSourc
                 glsafe(::glGetShaderInfoLog(id, params, &params, msg.data()));
                 BOOST_LOG_TRIVIAL(error) << "Unable to compile " << shader_type_as_string(type) << " shader of shader program '" << name << "':\n" << msg.data();
 
-                // release shader
+                // release shaders
                 release_shaders(shader_ids);
                 return false;
             }
@@ -173,13 +175,10 @@ bool GLShaderProgram::init_from_texts(const std::string& name, const ShaderSourc
     return true;
 }
 
-bool GLShaderProgram::start_using() const
+void GLShaderProgram::start_using() const
 {
-    if (m_id == 0)
-        return false;
-
+    assert(m_id > 0);
     glsafe(::glUseProgram(m_id));
-    return true;
 }
 
 void GLShaderProgram::stop_using() const
@@ -212,6 +211,16 @@ bool GLShaderProgram::set_uniform(const char* name, float value) const
     return false;
 }
 
+bool GLShaderProgram::set_uniform(const char* name, const std::array<float, 2>& value) const
+{
+    int id = get_uniform_location(name);
+    if (id >= 0) {
+        glsafe(::glUniform2fv(id, 1, static_cast<const GLfloat*>(value.data())));
+        return true;
+    }
+    return false;
+}
+
 bool GLShaderProgram::set_uniform(const char* name, const std::array<float, 3>& value) const
 {
     int id = get_uniform_location(name);
@@ -236,8 +245,7 @@ bool GLShaderProgram::set_uniform(const char* name, const float* value, size_t s
 {
     if (size == 1)
         return set_uniform(name, value[0]);
-    else if (size < 5)
-    {
+    else if (size < 5) {
         int id = get_uniform_location(name);
         if (id >= 0) {
             if (size == 2)
@@ -268,6 +276,16 @@ bool GLShaderProgram::set_uniform(const char* name, const Transform3d& value) co
     return set_uniform(name, value.cast<float>());
 }
 
+bool GLShaderProgram::set_uniform(const char* name, const Matrix3f& value) const
+{
+    int id = get_uniform_location(name);
+    if (id >= 0) {
+        glsafe(::glUniformMatrix3fv(id, 1, GL_FALSE, static_cast<const GLfloat*>(value.data())));
+        return true;
+    }
+    return false;
+}
+
 int GLShaderProgram::get_attrib_location(const char* name) const
 {
     return (m_id > 0) ? ::glGetAttribLocation(m_id, name) : -1;
diff --git a/src/slic3r/GUI/GLShader.hpp b/src/slic3r/GUI/GLShader.hpp
index 23d04b22c..6994b91ca 100644
--- a/src/slic3r/GUI/GLShader.hpp
+++ b/src/slic3r/GUI/GLShader.hpp
@@ -37,17 +37,19 @@ public:
     const std::string& get_name() const { return m_name; }
     unsigned int get_id() const { return m_id; }
 
-    bool start_using() const;
+    void start_using() const;
     void stop_using() const;
 
     bool set_uniform(const char* name, int value) const;
     bool set_uniform(const char* name, bool value) const;
     bool set_uniform(const char* name, float value) const;
+    bool set_uniform(const char* name, const std::array<float, 2>& value) const;
     bool set_uniform(const char* name, const std::array<float, 3>& value) const;
     bool set_uniform(const char* name, const std::array<float, 4>& value) const;
     bool set_uniform(const char* name, const float* value, size_t size) const;
     bool set_uniform(const char* name, const Transform3f& value) const;
     bool set_uniform(const char* name, const Transform3d& value) const;
+    bool set_uniform(const char* name, const Matrix3f& value) const;
 
     // returns -1 if not found
     int get_attrib_location(const char* name) const;
diff --git a/src/slic3r/GUI/GLShadersManager.cpp b/src/slic3r/GUI/GLShadersManager.cpp
index e4d640722..feffaecde 100644
--- a/src/slic3r/GUI/GLShadersManager.cpp
+++ b/src/slic3r/GUI/GLShadersManager.cpp
@@ -1,9 +1,12 @@
 #include "libslic3r/libslic3r.h"
 #include "GLShadersManager.hpp"
+#include "3DScene.hpp"
 
 #include <cassert>
 #include <algorithm>
 
+#include <GL/glew.h>
+
 #if ENABLE_SHADERS_MANAGER
 
 namespace Slic3r {
@@ -71,6 +74,17 @@ GLShaderProgram* GLShadersManager::get_shader(const std::string& shader_name)
     return (it != m_shaders.end()) ? it->get() : nullptr;
 }
 
+GLShaderProgram* GLShadersManager::get_current_shader()
+{
+    GLint id = 0;
+    glsafe(::glGetIntegerv(GL_CURRENT_PROGRAM, &id));
+    if (id == 0)
+        return false;
+
+    auto it = std::find_if(m_shaders.begin(), m_shaders.end(), [id](std::unique_ptr<GLShaderProgram>& p) { return p->get_id() == id; });
+    return (it != m_shaders.end()) ? it->get() : nullptr;
+}
+
 } // namespace Slic3r
 
 #endif // ENABLE_SHADERS_MANAGER
diff --git a/src/slic3r/GUI/GLShadersManager.hpp b/src/slic3r/GUI/GLShadersManager.hpp
index 0c624f916..f30472b12 100644
--- a/src/slic3r/GUI/GLShadersManager.hpp
+++ b/src/slic3r/GUI/GLShadersManager.hpp
@@ -22,6 +22,9 @@ public:
 
     // returns nullptr if not found
     GLShaderProgram* get_shader(const std::string& shader_name);
+
+    // returns currently active shader, nullptr if none
+    GLShaderProgram* get_current_shader();
 };
 
 } // namespace Slic3r
diff --git a/src/slic3r/GUI/GUI_App.hpp b/src/slic3r/GUI/GUI_App.hpp
index c4082cbb2..9bd869781 100644
--- a/src/slic3r/GUI/GUI_App.hpp
+++ b/src/slic3r/GUI/GUI_App.hpp
@@ -218,8 +218,8 @@ public:
 #endif // ENABLE_THUMBNAIL_GENERATOR_DEBUG
 
 #if ENABLE_SHADERS_MANAGER
-    // returns nullptr if not found
     GLShaderProgram* get_shader(const std::string& shader_name) { return m_opengl_mgr.get_shader(shader_name); }
+    GLShaderProgram* get_current_shader() { return m_opengl_mgr.get_current_shader(); }
 #endif // ENABLE_SHADERS_MANAGER
 
 private:
@@ -240,6 +240,6 @@ private:
 DECLARE_APP(GUI_App)
 
 } // GUI
-} //Slic3r
+} // Slic3r
 
 #endif // slic3r_GUI_App_hpp_
diff --git a/src/slic3r/GUI/GUI_ObjectList.cpp b/src/slic3r/GUI/GUI_ObjectList.cpp
index b2283ba4a..419f64567 100644
--- a/src/slic3r/GUI/GUI_ObjectList.cpp
+++ b/src/slic3r/GUI/GUI_ObjectList.cpp
@@ -333,6 +333,34 @@ void ObjectList::get_selected_item_indexes(int& obj_idx, int& vol_idx, const wxD
     vol_idx =   type & itVolume ? m_objects_model->GetVolumeIdByItem(item) : -1;
 }
 
+void ObjectList::get_selection_indexes(std::vector<int>& obj_idxs, std::vector<int>& vol_idxs)
+{
+    wxDataViewItemArray sels;
+    GetSelections(sels);
+    assert(!sels.IsEmpty());
+
+    if (m_objects_model->GetItemType(sels[0]) & itVolume) {
+        for (wxDataViewItem item : sels) {
+            obj_idxs.emplace_back(m_objects_model->GetIdByItem(m_objects_model->GetTopParent(item)));
+
+            assert(m_objects_model->GetItemType(item) & itVolume);
+            vol_idxs.emplace_back(m_objects_model->GetVolumeIdByItem(item));
+        }
+    }
+    else {
+        for (wxDataViewItem item : sels) {
+            const ItemType type = m_objects_model->GetItemType(item);
+            assert(type & itObject | itInstance | itInstanceRoot);
+
+            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(), std::greater<int>());
+    obj_idxs.erase(std::unique(obj_idxs.begin(), obj_idxs.end()), obj_idxs.end());
+}
+
 int ObjectList::get_mesh_errors_count(const int obj_idx, const int vol_idx /*= -1*/) const
 {
     if (obj_idx < 0)
@@ -1744,6 +1772,15 @@ void ObjectList::append_menu_item_scale_selection_to_fit_print_volume(wxMenu* me
         [](wxCommandEvent&) { wxGetApp().plater()->scale_selection_to_fit_print_volume(); }, "", menu);
 }
 
+void ObjectList::append_menu_items_convert_unit(wxMenu* menu)
+{
+    append_menu_item(menu, wxID_ANY, _L("Convert from imperial unit"), _L("Convert from imperial unit"),
+        [](wxCommandEvent&) { wxGetApp().plater()->convert_unit(true); }, "", menu);
+
+    append_menu_item(menu, wxID_ANY, _L("Convert to imperial unit"), _L("Convert to imperial unit"),
+        [](wxCommandEvent&) { wxGetApp().plater()->convert_unit(false); }, "", menu);
+}
+
 void ObjectList::create_object_popupmenu(wxMenu *menu)
 {
 #ifdef __WXOSX__  
@@ -1751,6 +1788,7 @@ void ObjectList::create_object_popupmenu(wxMenu *menu)
 #endif // __WXOSX__
 
     append_menu_item_reload_from_disk(menu);
+    append_menu_items_convert_unit(menu);
     append_menu_item_export_stl(menu);
     append_menu_item_fix_through_netfabb(menu);
     append_menu_item_scale_selection_to_fit_print_volume(menu);
@@ -1775,6 +1813,7 @@ void ObjectList::create_sla_object_popupmenu(wxMenu *menu)
 #endif // __WXOSX__
 
     append_menu_item_reload_from_disk(menu);
+    append_menu_items_convert_unit(menu);
     append_menu_item_export_stl(menu);
     append_menu_item_fix_through_netfabb(menu);
     // rest of a object_sla_menu will be added later in:
@@ -1788,6 +1827,7 @@ void ObjectList::create_part_popupmenu(wxMenu *menu)
 #endif // __WXOSX__
 
     append_menu_item_reload_from_disk(menu);
+    append_menu_items_convert_unit(menu);
     append_menu_item_export_stl(menu);
     append_menu_item_fix_through_netfabb(menu);
 
@@ -4050,6 +4090,8 @@ void ObjectList::show_multi_selection_menu()
         return wxGetApp().plater()->can_reload_from_disk();
     }, wxGetApp().plater());
 
+    append_menu_items_convert_unit(menu);
+
     wxGetApp().plater()->PopupMenu(menu);
 }
 
diff --git a/src/slic3r/GUI/GUI_ObjectList.hpp b/src/slic3r/GUI/GUI_ObjectList.hpp
index 72e130737..a0370bd9d 100644
--- a/src/slic3r/GUI/GUI_ObjectList.hpp
+++ b/src/slic3r/GUI/GUI_ObjectList.hpp
@@ -210,6 +210,7 @@ public:
 
     // Get obj_idx and vol_idx values for the selected (by default) or an adjusted item
     void                get_selected_item_indexes(int& obj_idx, int& vol_idx, const wxDataViewItem& item = wxDataViewItem(0));
+    void                get_selection_indexes(std::vector<int>& obj_idxs, std::vector<int>& vol_idxs);
     // Get count of errors in the mesh
     int                 get_mesh_errors_count(const int obj_idx, const int vol_idx = -1) const;
     /* Get list of errors in the mesh. Return value is a string, used for the tooltip
@@ -252,6 +253,7 @@ public:
     void                append_menu_item_change_extruder(wxMenu* menu);
     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                create_object_popupmenu(wxMenu *menu);
     void                create_sla_object_popupmenu(wxMenu*menu);
     void                create_part_popupmenu(wxMenu*menu);
diff --git a/src/slic3r/GUI/OpenGLManager.hpp b/src/slic3r/GUI/OpenGLManager.hpp
index b64532024..fb3b33494 100644
--- a/src/slic3r/GUI/OpenGLManager.hpp
+++ b/src/slic3r/GUI/OpenGLManager.hpp
@@ -96,8 +96,8 @@ public:
     wxGLContext* init_glcontext(wxGLCanvas& canvas);
 
 #if ENABLE_SHADERS_MANAGER
-    // returns nullptr if not found
     GLShaderProgram* get_shader(const std::string& shader_name) { return m_shaders_manager.get_shader(shader_name); }
+    GLShaderProgram* get_current_shader() { return m_shaders_manager.get_current_shader(); }
 #endif // ENABLE_SHADERS_MANAGER
 
     static bool are_compressed_textures_supported() { return s_compressed_textures_supported; }
diff --git a/src/slic3r/GUI/Plater.cpp b/src/slic3r/GUI/Plater.cpp
index 6588e7eb8..4ca92a1cb 100644
--- a/src/slic3r/GUI/Plater.cpp
+++ b/src/slic3r/GUI/Plater.cpp
@@ -3751,6 +3751,9 @@ bool Plater::priv::init_common_menu(wxMenu* menu, const bool is_part/* = false*/
 
         menu->AppendSeparator();
 
+        // "Scale to print volume" makes a sense just for whole object
+        sidebar->obj_list()->append_menu_item_scale_selection_to_fit_print_volume(menu);
+
         q->Bind(wxEVT_UPDATE_UI, [this](wxUpdateUIEvent& evt) {
             const Selection& selection = get_selection();
             int instance_idx = selection.get_instance_idx();
@@ -3763,10 +3766,9 @@ bool Plater::priv::init_common_menu(wxMenu* menu, const bool is_part/* = false*/
             }, menu_item_printable->GetId());
     }
 
+    sidebar->obj_list()->append_menu_items_convert_unit(menu);
     sidebar->obj_list()->append_menu_item_fix_through_netfabb(menu);
 
-    sidebar->obj_list()->append_menu_item_scale_selection_to_fit_print_volume(menu);
-
     wxMenu* mirror_menu = new wxMenu();
     if (mirror_menu == nullptr)
         return false;
@@ -4604,6 +4606,37 @@ void Plater::scale_selection_to_fit_print_volume()
     p->scale_selection_to_fit_print_volume();
 }
 
+void Plater::convert_unit(bool from_imperial_unit)
+{
+    std::vector<int> obj_idxs, volume_idxs;
+    wxGetApp().obj_list()->get_selection_indexes(obj_idxs, volume_idxs);
+    if (obj_idxs.empty() && volume_idxs.empty())
+        return;
+
+    TakeSnapshot snapshot(this, from_imperial_unit ? _L("Convert from imperial units") : _L("Convert to imperial units"));
+    wxBusyCursor wait;
+
+    ModelObjectPtrs objects;
+    for (int obj_idx : obj_idxs) {
+        ModelObject *object = p->model.objects[obj_idx];
+        object->convert_units(objects, from_imperial_unit, volume_idxs);
+        remove(obj_idx);
+    }
+    p->load_model_objects(objects);
+    
+    Selection& selection = p->view3D->get_canvas3d()->get_selection();
+    size_t last_obj_idx = p->model.objects.size() - 1;
+
+    if (volume_idxs.empty()) {
+        for (size_t i = 0; i < objects.size(); ++i)
+            selection.add_object((unsigned int)(last_obj_idx - i), i == 0);
+    }
+    else {
+        for (int vol_idx : volume_idxs)
+            selection.add_volume(last_obj_idx, vol_idx, 0, false);
+    }
+}
+
 void Plater::cut(size_t obj_idx, size_t instance_idx, coordf_t z, bool keep_upper, bool keep_lower, bool rotate_lower)
 {
     wxCHECK_RET(obj_idx < p->model.objects.size(), "obj_idx out of bounds");
diff --git a/src/slic3r/GUI/Plater.hpp b/src/slic3r/GUI/Plater.hpp
index eb35750d3..9381ed163 100644
--- a/src/slic3r/GUI/Plater.hpp
+++ b/src/slic3r/GUI/Plater.hpp
@@ -212,6 +212,7 @@ public:
     void set_number_of_copies(/*size_t num*/);
     bool is_selection_empty() const;
     void scale_selection_to_fit_print_volume();
+    void convert_unit(bool from_imperial_unit);
 
     void cut(size_t obj_idx, size_t instance_idx, coordf_t z, bool keep_upper = true, bool keep_lower = true, bool rotate_lower = false);
 
diff --git a/src/slic3r/GUI/Search.cpp b/src/slic3r/GUI/Search.cpp
index 22ac7b70f..967f6c537 100644
--- a/src/slic3r/GUI/Search.cpp
+++ b/src/slic3r/GUI/Search.cpp
@@ -483,11 +483,18 @@ SearchDialog::SearchDialog(OptionsSearcher* searcher)
     search_list->GetMainWindow()->Bind(wxEVT_LEFT_DOWN, &SearchDialog::OnLeftDown, this);
 #endif //__WXMSW__
 
+    // Under OSX mouse and key states didn't fill after wxEVT_DATAVIEW_SELECTION_CHANGED call
+    // As a result, we can't to identify what kind of actions was done
+    // So, under OSX is used OnKeyDown function to navigate inside the list
+#ifdef __APPLE__
+    search_list->Bind(wxEVT_KEY_DOWN, &SearchDialog::OnKeyDown, this);
+#endif
+
     check_category->Bind(wxEVT_CHECKBOX, &SearchDialog::OnCheck, this);
     if (check_english)
         check_english ->Bind(wxEVT_CHECKBOX, &SearchDialog::OnCheck, this);
 
-    Bind(wxEVT_MOTION, &SearchDialog::OnMotion, this);
+//    Bind(wxEVT_MOTION, &SearchDialog::OnMotion, this);
     Bind(wxEVT_LEFT_DOWN, &SearchDialog::OnLeftDown, this);
 
     SetSizer(topSizer);
@@ -585,11 +592,16 @@ void SearchDialog::OnSelect(wxDataViewEvent& event)
     if (prevent_list_events)
         return;    
 
+    // Under OSX mouse and key states didn't fill after wxEVT_DATAVIEW_SELECTION_CHANGED call
+    // As a result, we can't to identify what kind of actions was done
+    // So, under OSX is used OnKeyDown function to navigate inside the list
+#ifndef __APPLE__
     // wxEVT_DATAVIEW_SELECTION_CHANGED is processed, when selection is changed after mouse click or press the Up/Down arrows
     // But this two cases should be processed in different way:
     // Up/Down arrows   -> leave it as it is (just a navigation)
     // LeftMouseClick   -> call the ProcessSelection function  
     if (wxGetMouseState().LeftIsDown())
+#endif //__APPLE__
         ProcessSelection(search_list->GetSelection());
 }