diff --git a/rtgui/CMakeLists.txt b/rtgui/CMakeLists.txt
index f5a20b88a..540b4d267 100644
--- a/rtgui/CMakeLists.txt
+++ b/rtgui/CMakeLists.txt
@@ -151,6 +151,7 @@ set(NONCLISOURCEFILES
     localcontrast.cc
     eventmapper.cc
     metadatapanel.cc
+    labgrid.cc
     )
 
 include_directories(BEFORE "${CMAKE_CURRENT_BINARY_DIR}")
diff --git a/rtgui/colortoning.cc b/rtgui/colortoning.cc
index 5034f90cc..396b4cb65 100644
--- a/rtgui/colortoning.cc
+++ b/rtgui/colortoning.cc
@@ -5,258 +5,11 @@
 #include "mycurve.h"
 #include "rtimage.h"
 #include "eventmapper.h"
+#include "labgrid.h"
 
 using namespace rtengine;
 using namespace rtengine::procparams;
 
-namespace {
-
-// adapted from the "color correction" module of Darktable. Original copyright follows
-/*
-    copyright (c) 2009--2010 johannes hanika.
-
-    darktable is free software: you can redistribute it and/or modify
-    it under the terms of the GNU General Public License as published by
-    the Free Software Foundation, either version 3 of the License, or
-    (at your option) any later version.
-
-    darktable is distributed in the hope that it will be useful,
-    but WITHOUT ANY WARRANTY; without even the implied warranty of
-    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-    GNU General Public License for more details.
-
-    You should have received a copy of the GNU General Public License
-    along with darktable.  If not, see <http://www.gnu.org/licenses/>.
-*/
-class LabGrid: public Gtk::DrawingArea {
-private:
-    rtengine::ProcEvent evt_;
-    enum State { OFF, HIGH, LOW };
-    State selected_;
-    float low_a_;
-    float high_a_;
-    float low_b_;
-    float high_b_;
-    ToolPanelListener *listener_;
-    bool edited_;
-    sigc::connection delay_conn_;
-    static const int inset = 2;
-
-    bool notify_listener()
-    {
-        if (listener_) {
-            listener_->panelChanged(evt_, Glib::ustring::compose("%1 %2 %3 %4", int(low_a_), int(low_b_), int(high_a_), int(high_b_)));
-        }
-        return false;
-    }
-    
-public:
-    LabGrid(rtengine::ProcEvent evt):
-        Gtk::DrawingArea(),
-        evt_(evt), selected_(OFF),
-        low_a_(0.f), high_a_(0.f), low_b_(0.f), high_b_(0.f),
-        listener_(nullptr),
-        edited_(false)
-    {
-        set_can_focus(true);
-        add_events(Gdk::EXPOSURE_MASK | Gdk::BUTTON_PRESS_MASK | Gdk::POINTER_MOTION_MASK);
-    }
-
-    void get_params(double &la, double &lb, double &ha, double &hb) const
-    {
-        la = low_a_;
-        ha = high_a_;
-        lb = low_b_;
-        hb = high_b_;
-    }
-
-    void set_params(double la, double lb, double ha, double hb, bool notify)
-    {
-        low_a_ = la;
-        low_b_ = lb;
-        high_a_ = ha;
-        high_b_ = hb;
-        queue_draw();
-        if (notify) {
-            notify_listener();
-        }
-    }
-
-    void set_edited(bool yes)
-    {
-        edited_ = yes;
-    }
-
-
-    bool get_edited() const
-    {
-        return edited_;
-    }
-
-    void set_listener(ToolPanelListener *l)
-    {
-        listener_ = l;
-    }
-
-    bool on_draw(const ::Cairo::RefPtr<Cairo::Context> &crf)
-    {
-        int width = get_allocated_width();
-        int height = get_allocated_height();
-        Cairo::RefPtr<Cairo::ImageSurface> cst =
-            Cairo::ImageSurface::create(Cairo::FORMAT_ARGB32, width, height);
-        Cairo::RefPtr<Cairo::Context> cr = Cairo::Context::create(cst);
-        // clear bg
-        cr->set_source_rgb(.2, .2, .2);
-        cr->paint();
-
-        cr->translate(inset, inset);
-        cr->set_antialias(Cairo::ANTIALIAS_NONE);
-        width -= 2 * inset;
-        height -= 2 * inset;
-        // flip y:
-        cr->translate(0, height);
-        cr->scale(1., -1.);
-        const int cells = 8;
-        float step = rtengine::ColorToningParams::LABGRID_CORR_MAX / float(cells/2);
-        for (int j = 0; j < cells; j++) {
-            for (int i = 0; i < cells; i++) {
-                float R, G, B;
-                float x, y, z;
-                int ii = i - cells/2;
-                int jj = j - cells/2;
-                float a = step * (ii + 0.5);
-                float b = step * (jj + 0.5);
-                Color::Lab2XYZ(25000.f, a, b, x, y, z);
-                Color::xyz2srgb(x, y, z, R, G, B);
-                cr->set_source_rgb(R / 65535.f, G / 65535.f, B / 65535.f);
-                cr->rectangle(width * i / float(cells), height * j / float(cells), width / float(cells) - 1, height / float(cells) - 1);
-                cr->fill();
-            }
-        }
-        cr->set_antialias(Cairo::ANTIALIAS_DEFAULT);
-        float loa, hia, lob, hib;
-        loa = .5f * (width + width * low_a_ / rtengine::ColorToningParams::LABGRID_CORR_MAX);
-        hia = .5f * (width + width * high_a_ / rtengine::ColorToningParams::LABGRID_CORR_MAX);
-        lob = .5f * (height + height * low_b_ / rtengine::ColorToningParams::LABGRID_CORR_MAX);
-        hib = .5f * (height + height * high_b_ / rtengine::ColorToningParams::LABGRID_CORR_MAX);
-        cr->set_line_width(2.);
-        cr->set_source_rgb(0.6, 0.6, 0.6);
-        cr->move_to(loa, lob);
-        cr->line_to(hia, hib);
-        cr->stroke();
-
-        cr->set_source_rgb(0.1, 0.1, 0.1);
-        if (selected_ == LOW) {
-            cr->arc(loa, lob, 5, 0, 2. * rtengine::RT_PI);
-        } else {
-            cr->arc(loa, lob, 3, 0, 2. * rtengine::RT_PI);
-        }
-        cr->fill();
-
-        cr->set_source_rgb(0.9, 0.9, 0.9);
-        if (selected_ == HIGH) {
-            cr->arc(hia, hib, 5, 0, 2. * rtengine::RT_PI);
-        } else {
-            cr->arc(hia, hib, 3, 0, 2. * rtengine::RT_PI);
-        }
-        cr->fill();
-
-        crf->set_source(cst, 0, 0);
-        crf->paint();
-        
-        return true;
-    }
-    
-    bool on_button_press_event(GdkEventButton *event)
-    {
-        if (event->button == 1 && event->type == GDK_2BUTTON_PRESS) {
-            switch (selected_) {
-            case OFF:
-                low_a_ = low_b_ = high_a_ = high_b_ = 0.f;
-                break;
-            case LOW:
-                low_a_ = low_b_ = 0.f;
-                break;
-            case HIGH:
-                high_a_ = high_b_ = 0.f;
-                break;
-            }
-            edited_ = true;
-            queue_draw();
-            notify_listener();
-        }
-        return true;
-    }
-    
-    bool on_motion_notify_event(GdkEventMotion *event)
-    {
-        if (delay_conn_.connected()) {
-            delay_conn_.disconnect();
-        }
-        
-        int width = get_allocated_width() - 2 * inset, height = get_allocated_height() - 2 * inset;
-        const float mouse_x = std::min(std::max(event->x - inset, 0.), double(width));
-        const float mouse_y = std::min(std::max(height - 1 - event->y + inset, 0.), double(height));
-        const float ma = (2.0 * mouse_x - width) / (float)width;
-        const float mb = (2.0 * mouse_y - height) / (float)height;
-        bool refresh = selected_ != OFF;
-        if (event->state & GDK_BUTTON1_MASK) {
-            if (selected_ == LOW) {
-                low_a_ = ma * rtengine::ColorToningParams::LABGRID_CORR_MAX;
-                low_b_ = mb * rtengine::ColorToningParams::LABGRID_CORR_MAX;
-            } else if (selected_ == HIGH) {
-                high_a_ = ma * rtengine::ColorToningParams::LABGRID_CORR_MAX;
-                high_b_ = mb * rtengine::ColorToningParams::LABGRID_CORR_MAX;
-            }
-        } else {
-            selected_ = OFF;
-            float la = low_a_ / rtengine::ColorToningParams::LABGRID_CORR_MAX;
-            float lb = low_b_ / rtengine::ColorToningParams::LABGRID_CORR_MAX;
-            float ha = high_a_ / rtengine::ColorToningParams::LABGRID_CORR_MAX;
-            float hb = high_b_ / rtengine::ColorToningParams::LABGRID_CORR_MAX;
-            const float thrs = 0.05f;
-            const float distlo = (la - ma) * (la - ma) + (lb - mb) * (lb - mb);
-            const float disthi = (ha - ma) * (ha - ma) + (hb - mb) * (hb - mb);
-            if (distlo < thrs * thrs && distlo < disthi) {
-                selected_ = LOW;
-            } else if (disthi < thrs * thrs && disthi <= distlo) {
-                selected_ = HIGH;
-            }
-        }
-        if (selected_ != OFF) {
-            grab_focus();
-            if (options.adjusterMinDelay == 0) {
-                notify_listener();
-            } else {
-                delay_conn_ = Glib::signal_timeout().connect(sigc::mem_fun(*this, &LabGrid::notify_listener), options.adjusterMinDelay);
-            }
-        }
-        if (refresh) {
-            queue_draw();
-        }
-        return true;
-    }
-    
-    Gtk::SizeRequestMode get_request_mode_vfunc() const
-    {
-        return Gtk::SIZE_REQUEST_HEIGHT_FOR_WIDTH;
-    }
-
-    void get_preferred_width_vfunc(int &minimum_width, int &natural_width) const
-    {
-        minimum_width = 50;
-        natural_width = 200;
-    }
-
-    void get_preferred_height_for_width_vfunc (int width, int &minimum_height, int &natural_height) const
-    {
-        minimum_height = natural_height = width;
-    }
-};
-
-
-} // namespace
-
 
 ColorToning::ColorToning () : FoldableToolPanel(this, "colortoning", M("TP_COLORTONING_LABEL"), false, true)
 {
diff --git a/rtgui/labgrid.cc b/rtgui/labgrid.cc
new file mode 100644
index 000000000..7cb752bb6
--- /dev/null
+++ b/rtgui/labgrid.cc
@@ -0,0 +1,263 @@
+/** -*- C++ -*-
+ *  
+ *  This file is part of RawTherapee.
+ *
+ *  Copyright (c) 2017 Alberto Griggio <alberto.griggio@gmail.com>
+ *
+ *  RawTherapee is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  RawTherapee is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with RawTherapee.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+// adapted from the "color correction" module of Darktable. Original copyright follows
+/*
+    copyright (c) 2009--2010 johannes hanika.
+
+    darktable is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    darktable is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with darktable.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "labgrid.h"
+
+using rtengine::Color;
+
+
+bool LabGrid::notify_listener()
+{
+    if (listener_) {
+        listener_->panelChanged(evt_, Glib::ustring::compose("%1 %2 %3 %4", int(low_a_), int(low_b_), int(high_a_), int(high_b_)));
+    }
+    return false;
+}
+    
+
+LabGrid::LabGrid(rtengine::ProcEvent evt):
+    Gtk::DrawingArea(),
+    evt_(evt), selected_(OFF),
+    low_a_(0.f), high_a_(0.f), low_b_(0.f), high_b_(0.f),
+    listener_(nullptr),
+    edited_(false)
+{
+    set_can_focus(true);
+    add_events(Gdk::EXPOSURE_MASK | Gdk::BUTTON_PRESS_MASK | Gdk::POINTER_MOTION_MASK);
+}
+
+
+void LabGrid::get_params(double &la, double &lb, double &ha, double &hb) const
+{
+    la = low_a_;
+    ha = high_a_;
+    lb = low_b_;
+    hb = high_b_;
+}
+
+
+void LabGrid::set_params(double la, double lb, double ha, double hb, bool notify)
+{
+    low_a_ = la;
+    low_b_ = lb;
+    high_a_ = ha;
+    high_b_ = hb;
+    queue_draw();
+    if (notify) {
+        notify_listener();
+    }
+}
+
+
+void LabGrid::set_edited(bool yes)
+{
+    edited_ = yes;
+}
+
+
+bool LabGrid::get_edited() const
+{
+    return edited_;
+}
+
+
+void LabGrid::set_listener(ToolPanelListener *l)
+{
+    listener_ = l;
+}
+
+
+bool LabGrid::on_draw(const ::Cairo::RefPtr<Cairo::Context> &crf)
+{
+    int width = get_allocated_width();
+    int height = get_allocated_height();
+    Cairo::RefPtr<Cairo::ImageSurface> cst =
+        Cairo::ImageSurface::create(Cairo::FORMAT_ARGB32, width, height);
+    Cairo::RefPtr<Cairo::Context> cr = Cairo::Context::create(cst);
+    // clear bg
+    cr->set_source_rgb(.2, .2, .2);
+    cr->paint();
+    
+    cr->translate(inset, inset);
+    cr->set_antialias(Cairo::ANTIALIAS_NONE);
+    width -= 2 * inset;
+    height -= 2 * inset;
+    // flip y:
+    cr->translate(0, height);
+    cr->scale(1., -1.);
+    const int cells = 8;
+    float step = rtengine::ColorToningParams::LABGRID_CORR_MAX / float(cells/2);
+    for (int j = 0; j < cells; j++) {
+        for (int i = 0; i < cells; i++) {
+            float R, G, B;
+            float x, y, z;
+            int ii = i - cells/2;
+            int jj = j - cells/2;
+            float a = step * (ii + 0.5);
+            float b = step * (jj + 0.5);
+            Color::Lab2XYZ(25000.f, a, b, x, y, z);
+            Color::xyz2srgb(x, y, z, R, G, B);
+            cr->set_source_rgb(R / 65535.f, G / 65535.f, B / 65535.f);
+            cr->rectangle(width * i / float(cells), height * j / float(cells), width / float(cells) - 1, height / float(cells) - 1);
+            cr->fill();
+        }
+    }
+    cr->set_antialias(Cairo::ANTIALIAS_DEFAULT);
+    float loa, hia, lob, hib;
+    loa = .5f * (width + width * low_a_ / rtengine::ColorToningParams::LABGRID_CORR_MAX);
+    hia = .5f * (width + width * high_a_ / rtengine::ColorToningParams::LABGRID_CORR_MAX);
+    lob = .5f * (height + height * low_b_ / rtengine::ColorToningParams::LABGRID_CORR_MAX);
+    hib = .5f * (height + height * high_b_ / rtengine::ColorToningParams::LABGRID_CORR_MAX);
+    cr->set_line_width(2.);
+    cr->set_source_rgb(0.6, 0.6, 0.6);
+    cr->move_to(loa, lob);
+    cr->line_to(hia, hib);
+    cr->stroke();
+
+    cr->set_source_rgb(0.1, 0.1, 0.1);
+    if (selected_ == LOW) {
+        cr->arc(loa, lob, 5, 0, 2. * rtengine::RT_PI);
+    } else {
+        cr->arc(loa, lob, 3, 0, 2. * rtengine::RT_PI);
+    }
+    cr->fill();
+
+    cr->set_source_rgb(0.9, 0.9, 0.9);
+    if (selected_ == HIGH) {
+        cr->arc(hia, hib, 5, 0, 2. * rtengine::RT_PI);
+    } else {
+        cr->arc(hia, hib, 3, 0, 2. * rtengine::RT_PI);
+    }
+    cr->fill();
+
+    crf->set_source(cst, 0, 0);
+    crf->paint();
+        
+    return true;
+}
+
+
+bool LabGrid::on_button_press_event(GdkEventButton *event)
+{
+    if (event->button == 1 && event->type == GDK_2BUTTON_PRESS) {
+        switch (selected_) {
+        case OFF:
+            low_a_ = low_b_ = high_a_ = high_b_ = 0.f;
+            break;
+        case LOW:
+            low_a_ = low_b_ = 0.f;
+            break;
+        case HIGH:
+            high_a_ = high_b_ = 0.f;
+            break;
+        }
+        edited_ = true;
+        queue_draw();
+        notify_listener();
+    }
+    return true;
+}
+    
+
+bool LabGrid::on_motion_notify_event(GdkEventMotion *event)
+{
+    if (delay_conn_.connected()) {
+        delay_conn_.disconnect();
+    }
+        
+    int width = get_allocated_width() - 2 * inset, height = get_allocated_height() - 2 * inset;
+    const float mouse_x = std::min(std::max(event->x - inset, 0.), double(width));
+    const float mouse_y = std::min(std::max(height - 1 - event->y + inset, 0.), double(height));
+    const float ma = (2.0 * mouse_x - width) / (float)width;
+    const float mb = (2.0 * mouse_y - height) / (float)height;
+    bool refresh = selected_ != OFF;
+    if (event->state & GDK_BUTTON1_MASK) {
+        if (selected_ == LOW) {
+            low_a_ = ma * rtengine::ColorToningParams::LABGRID_CORR_MAX;
+            low_b_ = mb * rtengine::ColorToningParams::LABGRID_CORR_MAX;
+        } else if (selected_ == HIGH) {
+            high_a_ = ma * rtengine::ColorToningParams::LABGRID_CORR_MAX;
+            high_b_ = mb * rtengine::ColorToningParams::LABGRID_CORR_MAX;
+        }
+    } else {
+        selected_ = OFF;
+        float la = low_a_ / rtengine::ColorToningParams::LABGRID_CORR_MAX;
+        float lb = low_b_ / rtengine::ColorToningParams::LABGRID_CORR_MAX;
+        float ha = high_a_ / rtengine::ColorToningParams::LABGRID_CORR_MAX;
+        float hb = high_b_ / rtengine::ColorToningParams::LABGRID_CORR_MAX;
+        const float thrs = 0.05f;
+        const float distlo = (la - ma) * (la - ma) + (lb - mb) * (lb - mb);
+        const float disthi = (ha - ma) * (ha - ma) + (hb - mb) * (hb - mb);
+        if (distlo < thrs * thrs && distlo < disthi) {
+            selected_ = LOW;
+        } else if (disthi < thrs * thrs && disthi <= distlo) {
+            selected_ = HIGH;
+        }
+    }
+    if (selected_ != OFF) {
+        grab_focus();
+        if (options.adjusterMinDelay == 0) {
+            notify_listener();
+        } else {
+            delay_conn_ = Glib::signal_timeout().connect(sigc::mem_fun(*this, &LabGrid::notify_listener), options.adjusterMinDelay);
+        }
+    }
+    if (refresh) {
+        queue_draw();
+    }
+    return true;
+}
+    
+
+Gtk::SizeRequestMode LabGrid::get_request_mode_vfunc() const
+{
+    return Gtk::SIZE_REQUEST_HEIGHT_FOR_WIDTH;
+}
+
+
+void LabGrid::get_preferred_width_vfunc(int &minimum_width, int &natural_width) const
+{
+    minimum_width = 50;
+    natural_width = 200;
+}
+
+
+void LabGrid::get_preferred_height_for_width_vfunc(int width, int &minimum_height, int &natural_height) const
+{
+    minimum_height = natural_height = width;
+}
diff --git a/rtgui/labgrid.h b/rtgui/labgrid.h
new file mode 100644
index 000000000..dcb34bcc3
--- /dev/null
+++ b/rtgui/labgrid.h
@@ -0,0 +1,78 @@
+/** -*- C++ -*-
+ *  
+ *  This file is part of RawTherapee.
+ *
+ *  Copyright (c) 2017 Alberto Griggio <alberto.griggio@gmail.com>
+ *
+ *  RawTherapee is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  RawTherapee is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with RawTherapee.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+// adapted from the "color correction" module of Darktable. Original copyright follows
+/*
+    copyright (c) 2009--2010 johannes hanika.
+
+    darktable is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    darktable is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with darktable.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#pragma once
+
+#include <gtkmm.h>
+#include "eventmapper.h"
+#include "toolpanel.h"
+
+
+class LabGrid: public Gtk::DrawingArea {
+private:
+    rtengine::ProcEvent evt_;
+    enum State { OFF, HIGH, LOW };
+    State selected_;
+    float low_a_;
+    float high_a_;
+    float low_b_;
+    float high_b_;
+    ToolPanelListener *listener_;
+    bool edited_;
+    sigc::connection delay_conn_;
+    static const int inset = 2;
+
+    bool notify_listener();
+    
+public:
+    LabGrid(rtengine::ProcEvent evt);
+
+    void get_params(double &la, double &lb, double &ha, double &hb) const;
+    void set_params(double la, double lb, double ha, double hb, bool notify);
+    void set_edited(bool yes);
+    bool get_edited() const;
+    void set_listener(ToolPanelListener *l);
+
+    bool on_draw(const ::Cairo::RefPtr<Cairo::Context> &crf);
+    bool on_button_press_event(GdkEventButton *event);
+    bool on_motion_notify_event(GdkEventMotion *event);
+    Gtk::SizeRequestMode get_request_mode_vfunc() const;
+    void get_preferred_width_vfunc(int &minimum_width, int &natural_width) const;
+    void get_preferred_height_for_width_vfunc (int width, int &minimum_height, int &natural_height) const;
+};
+