diff --git a/src/slic3r/GUI/GLCanvas3D.cpp b/src/slic3r/GUI/GLCanvas3D.cpp
index 6021c42c32..d276bcb967 100644
--- a/src/slic3r/GUI/GLCanvas3D.cpp
+++ b/src/slic3r/GUI/GLCanvas3D.cpp
@@ -99,49 +99,6 @@ float RetinaHelper::get_scale_factor() { return float(m_window->GetContentScaleF
 #undef Convex
 #endif
 
-Size::Size()
-    : m_width(0)
-    , m_height(0)
-{
-}
-
-Size::Size(int width, int height, float scale_factor)
-    : m_width(width)
-    , m_height(height)
-    , m_scale_factor(scale_factor)
-{
-}
-
-int Size::get_width() const
-{
-    return m_width;
-}
-
-void Size::set_width(int width)
-{
-    m_width = width;
-}
-
-int Size::get_height() const
-{
-    return m_height;
-}
-
-void Size::set_height(int height)
-{
-    m_height = height;
-}
-
-int Size::get_scale_factor() const
-{
-    return m_scale_factor;
-}
-
-void Size::set_scale_factor(int scale_factor)
-{
-    m_scale_factor = scale_factor;
-}
-
 GLCanvas3D::LayersEditing::~LayersEditing()
 {
     if (m_z_texture_id != 0) {
@@ -418,7 +375,6 @@ void GLCanvas3D::LayersEditing::render_profile(const Rect& bar_rect)
     // Make the vertical bar a bit wider so the layer height curve does not touch the edge of the bar region.
     const float scale_x = bar_rect.get_width() / float(1.12 * m_slicing_parameters->max_layer_height);
     const float scale_y = bar_rect.get_height() / m_object_max_z;
-    const float x = bar_rect.get_left() + float(m_slicing_parameters->layer_height) * scale_x;
 
 #if ENABLE_GLBEGIN_GLEND_REMOVAL
     const bool bar_rect_changed = m_profile.old_bar_rect != bar_rect;
@@ -426,17 +382,18 @@ void GLCanvas3D::LayersEditing::render_profile(const Rect& bar_rect)
 
     // Baseline
     if (!m_profile.baseline.is_initialized() || bar_rect_changed) {
-        m_profile.old_bar_rect = bar_rect;
+        m_profile.baseline.reset();
 
         GLModel::Geometry init_data;
-        init_data.format = { GLModel::Geometry::EPrimitiveType::Lines, GLModel::Geometry::EVertexLayout::P3, GLModel::Geometry::EIndexType::USHORT };
+        init_data.format = { GLModel::Geometry::EPrimitiveType::Lines, GLModel::Geometry::EVertexLayout::P2, GLModel::Geometry::EIndexType::USHORT };
         init_data.color = ColorRGBA::BLACK();
         init_data.vertices.reserve(2 * GLModel::Geometry::vertex_stride_floats(init_data.format));
         init_data.indices.reserve(2 * GLModel::Geometry::index_stride_bytes(init_data.format));
 
         // vertices
-        init_data.add_vertex(Vec3f(x, bar_rect.get_bottom(), 0.0f));
-        init_data.add_vertex(Vec3f(x, bar_rect.get_top(), 0.0f));
+        const float x = bar_rect.get_left() + float(m_slicing_parameters->layer_height) * scale_x;
+        init_data.add_vertex(Vec2f(x, bar_rect.get_bottom()));
+        init_data.add_vertex(Vec2f(x, bar_rect.get_top()));
 
         // indices
         init_data.add_ushort_line(0, 1);
@@ -449,16 +406,15 @@ void GLCanvas3D::LayersEditing::render_profile(const Rect& bar_rect)
         m_profile.profile.reset();
 
         GLModel::Geometry init_data;
-        init_data.format = { GLModel::Geometry::EPrimitiveType::LineStrip, GLModel::Geometry::EVertexLayout::P3, GLModel::Geometry::EIndexType::UINT };
+        init_data.format = { GLModel::Geometry::EPrimitiveType::LineStrip, GLModel::Geometry::EVertexLayout::P2, GLModel::Geometry::EIndexType::UINT };
         init_data.color = ColorRGBA::BLUE();
         init_data.vertices.reserve(m_layer_height_profile.size() * GLModel::Geometry::vertex_stride_floats(init_data.format));
         init_data.indices.reserve(m_layer_height_profile.size() * GLModel::Geometry::index_stride_bytes(init_data.format));
 
         // vertices + indices
         for (unsigned int i = 0; i < (unsigned int)m_layer_height_profile.size(); i += 2) {
-            init_data.add_vertex(Vec3f(bar_rect.get_left() + float(m_layer_height_profile[i + 1]) * scale_x, 
-                                       bar_rect.get_bottom() + float(m_layer_height_profile[i]) * scale_y,
-                                       0.0f));
+            init_data.add_vertex(Vec2f(bar_rect.get_left() + float(m_layer_height_profile[i + 1]) * scale_x,
+                                       bar_rect.get_bottom() + float(m_layer_height_profile[i]) * scale_y));
             init_data.add_uint_index(i / 2);
         }
 
@@ -473,6 +429,8 @@ void GLCanvas3D::LayersEditing::render_profile(const Rect& bar_rect)
         shader->stop_using();
     }
 #else
+    const float x = bar_rect.get_left() + float(m_slicing_parameters->layer_height) * scale_x;
+
     // Baseline
     glsafe(::glColor3f(0.0f, 0.0f, 0.0f));
     ::glBegin(GL_LINE_STRIP);
diff --git a/src/slic3r/GUI/GLCanvas3D.hpp b/src/slic3r/GUI/GLCanvas3D.hpp
index e5f1dcfc7b..6b14430e8e 100644
--- a/src/slic3r/GUI/GLCanvas3D.hpp
+++ b/src/slic3r/GUI/GLCanvas3D.hpp
@@ -59,25 +59,24 @@ class RetinaHelper;
 
 class Size
 {
-    int m_width;
-    int m_height;
-    float m_scale_factor;
+    int m_width{ 0 };
+    int m_height{ 0 };
+    float m_scale_factor{ 1.0f };
 
 public:
-    Size();
-    Size(int width, int height, float scale_factor = 1.0);
+    Size() = default;
+    Size(int width, int height, float scale_factor = 1.0f) : m_width(width), m_height(height), m_scale_factor(scale_factor) {}
 
-    int get_width() const;
-    void set_width(int width);
+    int get_width() const { return m_width; }
+    void set_width(int width) { m_width = width; }
 
-    int get_height() const;
-    void set_height(int height);
+    int get_height() const { return m_height; }
+    void set_height(int height) { m_height = height; }
 
-    int get_scale_factor() const;
-    void set_scale_factor(int height);
+    float get_scale_factor() const { return m_scale_factor; }
+    void set_scale_factor(float factor) { m_scale_factor = factor; }
 };
 
-
 class RenderTimerEvent : public wxEvent
 {
 public:
diff --git a/src/slic3r/GUI/GLModel.cpp b/src/slic3r/GUI/GLModel.cpp
index 1bebabb32f..7f18c5176e 100644
--- a/src/slic3r/GUI/GLModel.cpp
+++ b/src/slic3r/GUI/GLModel.cpp
@@ -356,8 +356,11 @@ void GLModel::init_from(const Geometry& data)
 #endif // ENABLE_GLBEGIN_GLEND_REMOVAL
 {
 #if ENABLE_GLBEGIN_GLEND_REMOVAL
-    if (is_initialized()) // call reset() if you want to reuse this model
+    if (is_initialized()) {
+        // call reset() if you want to reuse this model
+        assert(false);
         return;
+    }
 
     if (data.vertices.empty() || data.indices.empty()) {
         assert(false);
@@ -427,8 +430,11 @@ void GLModel::init_from(const indexed_triangle_set& its, const BoundingBoxf3 &bb
 #endif // ENABLE_GLBEGIN_GLEND_REMOVAL
 {
 #if ENABLE_GLBEGIN_GLEND_REMOVAL
-    if (is_initialized()) // call reset() if you want to reuse this model
+    if (is_initialized()) {
+        // call reset() if you want to reuse this model
+        assert(false);
         return;
+    }
 
     if (its.vertices.empty() || its.indices.empty()){
         assert(false);
@@ -500,8 +506,11 @@ void GLModel::init_from(const indexed_triangle_set& its)
 void GLModel::init_from(const Polygons& polygons, float z)
 {
 #if ENABLE_GLBEGIN_GLEND_REMOVAL
-    if (is_initialized()) // call reset() if you want to reuse this model
+    if (is_initialized()) {
+        // call reset() if you want to reuse this model
+        assert(false);
         return;
+    }
 
     if (polygons.empty()) {
         assert(false);
@@ -582,7 +591,8 @@ bool GLModel::init_from_file(const std::string& filename)
 #if ENABLE_GLBEGIN_GLEND_REMOVAL
     init_from(model.mesh());
 #else
-    init_from(model.mesh().its, mesh.bounding_box());
+    const TriangleMesh& mesh = model.mesh();
+    init_from(mesh.its, mesh.bounding_box());
 #endif // ENABLE_GLBEGIN_GLEND_REMOVAL
 
     m_filename = filename;
diff --git a/src/slic3r/GUI/GLShadersManager.cpp b/src/slic3r/GUI/GLShadersManager.cpp
index 4e14eaf7f9..3ed92d56d4 100644
--- a/src/slic3r/GUI/GLShadersManager.cpp
+++ b/src/slic3r/GUI/GLShadersManager.cpp
@@ -34,8 +34,7 @@ std::pair<bool, std::string> GLShadersManager::init()
     bool valid = true;
 
 #if ENABLE_GLBEGIN_GLEND_REMOVAL
-    // basic shader, used to render selection bbox, gizmo cut plane and grabbers connections,
-    // gizmo move grabbers connections, gizmo scale grabbers connections
+    // basic shader, used to render all what was previously rendered using the immediate mode
     valid &= append_shader("flat", { "flat.vs", "flat.fs" });
 #endif // ENABLE_GLBEGIN_GLEND_REMOVAL
     // used to render bed axes and model, selection hints, gcode sequential view marker model, preview shells, options in gcode preview
diff --git a/src/slic3r/GUI/Gizmos/GLGizmosManager.hpp b/src/slic3r/GUI/Gizmos/GLGizmosManager.hpp
index fe4f81bd78..8d268723bc 100644
--- a/src/slic3r/GUI/Gizmos/GLGizmosManager.hpp
+++ b/src/slic3r/GUI/Gizmos/GLGizmosManager.hpp
@@ -35,14 +35,14 @@ public:
     Rect(float left, float top, float right, float bottom) : m_left(left) , m_top(top) , m_right(right) , m_bottom(bottom) {}
 
 #if ENABLE_GLBEGIN_GLEND_REMOVAL
-    bool operator == (const Rect& other) {
+    bool operator == (const Rect& other) const {
         if (std::abs(m_left - other.m_left) > EPSILON) return false;
         if (std::abs(m_top - other.m_top) > EPSILON) return false;
         if (std::abs(m_right - other.m_right) > EPSILON) return false;
         if (std::abs(m_bottom - other.m_bottom) > EPSILON) return false;
         return true;
     }
-    bool operator != (const Rect& other) { return !operator==(other); }
+    bool operator != (const Rect& other) const { return !operator==(other); }
 #endif // ENABLE_GLBEGIN_GLEND_REMOVAL
 
     float get_left() const { return m_left; }