diff --git a/src/app/script/dialog_class.cpp b/src/app/script/dialog_class.cpp
index 5a4e65f27..66c40722f 100644
--- a/src/app/script/dialog_class.cpp
+++ b/src/app/script/dialog_class.cpp
@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2018-2019  Igara Studio S.A.
+// Copyright (C) 2018-2020  Igara Studio S.A.
 // Copyright (C) 2018  David Capello
 //
 // This program is distributed under the terms of
@@ -103,11 +103,11 @@ struct Dialog {
 
 };
 
-template<typename Signal,
+template<typename...Args,
          typename Callback>
 void Dialog_connect_signal(lua_State* L,
                            int dlgIdx,
-                           Signal& signal,
+                           obs::signal<void(Args...)>& signal,
                            Callback callback)
 {
   auto dlg = get_obj<Dialog>(L, dlgIdx);
@@ -124,7 +124,7 @@ void Dialog_connect_signal(lua_State* L,
   lua_pop(L, 1);           // Pop the uservalue
 
   signal.connect(
-    base::Bind<void>([=]() {
+    [=](Args...args) {
       // In case that the dialog is hidden, we cannot access to the
       // global LUA_REGISTRYINDEX to get its reference.
       if (dlg->showRef == LUA_REFNIL)
@@ -141,7 +141,7 @@ void Dialog_connect_signal(lua_State* L,
         // lua_pcall() (that table is like an "event data" parameter
         // for the function).
         lua_newtable(L);
-        callback(L);
+        callback(L, std::forward<Args>(args)...);
 
         if (lua_isfunction(L, -2)) {
           if (lua_pcall(L, 1, 0, 0)) {
@@ -164,7 +164,7 @@ void Dialog_connect_signal(lua_State* L,
           ->scriptEngine()
           ->consolePrint(ex.what());
       }
-    }));
+    });
 }
 
 int Dialog_new(lua_State* L)
@@ -193,7 +193,7 @@ int Dialog_new(lua_State* L)
     if (type == LUA_TFUNCTION) {
       Dialog_connect_signal(
         L, -2, dlg->window.Close,
-        [](lua_State* L){
+        [](lua_State*, CloseEvent&){
           // Do nothing
         });
     }
@@ -395,7 +395,7 @@ int Dialog_button_base(lua_State* L, T** outputWidget = nullptr)
       auto dlg = get_obj<Dialog>(L, 1);
       Dialog_connect_signal(
         L, 1, widget->Click,
-        [dlg, widget](lua_State* L){
+        [dlg, widget](lua_State* L, Event&){
           dlg->lastButton = widget;
         });
       closeWindowByDefault = false;
@@ -595,7 +595,10 @@ int Dialog_shades(lua_State* L)
     if (type == LUA_TFUNCTION) {
       Dialog_connect_signal(
         L, 1, widget->Click,
-        [widget](lua_State* L){
+        [widget](lua_State* L, ColorShades::ClickEvent& ev){
+          lua_pushinteger(L, (int)ev.button());
+          lua_setfield(L, -2, "button");
+
           const int i = widget->getHotEntry();
           const Shade shade = widget->getShade();
           if (i >= 0 && i < int(shade.size())) {
diff --git a/src/app/script/engine.cpp b/src/app/script/engine.cpp
index 5759af94e..7e122e68a 100644
--- a/src/app/script/engine.cpp
+++ b/src/app/script/engine.cpp
@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2018-2019  Igara Studio S.A.
+// Copyright (C) 2018-2020  Igara Studio S.A.
 // Copyright (C) 2001-2018  David Capello
 //
 // This program is distributed under the terms of
@@ -26,6 +26,7 @@
 #include "doc/blend_mode.h"
 #include "doc/color_mode.h"
 #include "filters/target.h"
+#include "ui/mouse_button.h"
 
 #include <fstream>
 #include <sstream>
@@ -341,6 +342,17 @@ Engine::Engine()
   setfield_integer(L, "GRAYA",   TARGET_GRAY_CHANNEL | TARGET_ALPHA_CHANNEL);
   lua_pop(L, 1);
 
+  lua_newtable(L);
+  lua_pushvalue(L, -1);
+  lua_setglobal(L, "MouseButton");
+  setfield_integer(L, "NONE",   (int)ui::kButtonNone);
+  setfield_integer(L, "LEFT",   (int)ui::kButtonLeft);
+  setfield_integer(L, "RIGHT",  (int)ui::kButtonRight);
+  setfield_integer(L, "MIDDLE", (int)ui::kButtonMiddle);
+  setfield_integer(L, "X1",     (int)ui::kButtonX1);
+  setfield_integer(L, "X2",     (int)ui::kButtonX2);
+  lua_pop(L, 1);
+
   // Register classes/prototypes
   register_brush_class(L);
   register_cel_class(L);
diff --git a/src/app/ui/color_popup.cpp b/src/app/ui/color_popup.cpp
index 9d07a3d77..1619fd536 100644
--- a/src/app/ui/color_popup.cpp
+++ b/src/app/ui/color_popup.cpp
@@ -408,7 +408,7 @@ void ColorPopup::onColorHexEntryChange(const app::Color& color)
     m_disableHexUpdate = false;
 }
 
-void ColorPopup::onSelectOldColor()
+void ColorPopup::onSelectOldColor(ColorShades::ClickEvent&)
 {
   Shade shade = m_oldAndNew.getShade();
   int hot = m_oldAndNew.getHotEntry();
diff --git a/src/app/ui/color_popup.h b/src/app/ui/color_popup.h
index 1aacd16d0..f687da5d2 100644
--- a/src/app/ui/color_popup.h
+++ b/src/app/ui/color_popup.h
@@ -53,7 +53,7 @@ namespace app {
     void onMakeFixed() override;
     void onColorSlidersChange(ColorSlidersChangeEvent& ev);
     void onColorHexEntryChange(const app::Color& color);
-    void onSelectOldColor();
+    void onSelectOldColor(ColorShades::ClickEvent& ev);
     void onSimpleColorClick();
     void onColorTypeClick();
     void onPaletteChange();
diff --git a/src/app/ui/color_shades.cpp b/src/app/ui/color_shades.cpp
index a0af5decf..598b64176 100644
--- a/src/app/ui/color_shades.cpp
+++ b/src/app/ui/color_shades.cpp
@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2019  Igara Studio S.A.
+// Copyright (C) 2019-2020  Igara Studio S.A.
 // Copyright (C) 2018  David Capello
 //
 // This program is distributed under the terms of
@@ -28,8 +28,8 @@
 #include "ui/paint_event.h"
 #include "ui/size_hint_event.h"
 #include "ui/system.h"
+#include <algorithm>
 
-#include <limits>
 
 namespace app {
 
@@ -147,11 +147,14 @@ bool ColorShades::onProcessMessage(ui::Message* msg)
       if (m_hotIndex >= 0 &&
           m_hotIndex < int(m_shade.size())) {
         switch (m_click) {
-          case ClickEntries:
-            Click();
+          case ClickEntries: {
+            ClickEvent ev(static_cast<ui::MouseMessage*>(msg)->button());
+            Click(ev);
+
             m_hotIndex = -1;
             invalidate();
             break;
+          }
           case DragAndDropEntries:
             m_dragIndex = m_hotIndex;
             m_dropBefore = false;
@@ -164,7 +167,10 @@ bool ColorShades::onProcessMessage(ui::Message* msg)
     case ui::kMouseUpMessage: {
       if (m_click == ClickWholeShade) {
         setSelected(true);
-        Click();
+
+        ClickEvent ev(static_cast<ui::MouseMessage*>(msg)->button());
+        Click(ev);
+
         closeWindow();
       }
 
diff --git a/src/app/ui/color_shades.h b/src/app/ui/color_shades.h
index 7d6326625..7917e4439 100644
--- a/src/app/ui/color_shades.h
+++ b/src/app/ui/color_shades.h
@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2019  Igara Studio S.A.
+// Copyright (C) 2019-2020  Igara Studio S.A.
 // Copyright (C) 2018  David Capello
 //
 // This program is distributed under the terms of
@@ -11,6 +11,7 @@
 
 #include "app/shade.h"
 #include "obs/signal.h"
+#include "ui/mouse_button.h"
 #include "ui/widget.h"
 
 namespace doc {
@@ -41,7 +42,15 @@ namespace app {
 
     int getHotEntry() const { return m_hotIndex; }
 
-    obs::signal<void()> Click;
+    class ClickEvent {
+    public:
+      ClickEvent(ui::MouseButton button) : m_button(button) { }
+      ui::MouseButton button() const { return m_button; }
+    private:
+      ui::MouseButton m_button;
+    };
+
+    obs::signal<void(ClickEvent&)> Click;
 
   private:
     void onInitTheme(ui::InitThemeEvent& ev) override;
diff --git a/src/app/ui/context_bar.cpp b/src/app/ui/context_bar.cpp
index cb438fb46..145f5d5c6 100644
--- a/src/app/ui/context_bar.cpp
+++ b/src/app/ui/context_bar.cpp
@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2018-2019  Igara Studio S.A.
+// Copyright (C) 2018-2020  Igara Studio S.A.
 // Copyright (C) 2001-2018  David Capello
 //
 // This program is distributed under the terms of
@@ -595,7 +595,7 @@ private:
         auto shadeWidget = new ColorShades(shade, ColorShades::ClickWholeShade);
         shadeWidget->setExpansive(true);
         shadeWidget->Click.connect(
-          [&]{
+          [&](ColorShades::ClickEvent&){
             m_shade.setShade(shade);
           });