diff --git a/data/widgets/cel_properties.xml b/data/widgets/cel_properties.xml
index 9f2d16800..519a84d38 100644
--- a/data/widgets/cel_properties.xml
+++ b/data/widgets/cel_properties.xml
@@ -5,7 +5,7 @@
 <window id="cel_properties" text="@.title">
   <grid id="properties_grid" columns="4">
     <label text="@.opacity" />
-    <slider min="0" max="255" id="opacity" cell_align="horizontal" width="128" cell_hspan="2" />
+    <opacityslider id="opacity" cell_align="horizontal" width="128" cell_hspan="2" />
     <button id="user_data" icon="icon_user_data" tooltip="@.user_data_tooltip" />
 
     <label text="@.zindex" />
diff --git a/src/app/CMakeLists.txt b/src/app/CMakeLists.txt
index ee42c8ab0..803a1a302 100644
--- a/src/app/CMakeLists.txt
+++ b/src/app/CMakeLists.txt
@@ -336,6 +336,7 @@ if(ENABLE_UI)
     file_selector.cpp
     modules/gfx.cpp
     modules/gui.cpp
+    ui/alpha_slider.cpp
     ui/app_menuitem.cpp
     ui/backup_indicator.cpp
     ui/browser_view.cpp
diff --git a/src/app/ui/alpha_slider.cpp b/src/app/ui/alpha_slider.cpp
new file mode 100644
index 000000000..a426a38c5
--- /dev/null
+++ b/src/app/ui/alpha_slider.cpp
@@ -0,0 +1,69 @@
+// Aseprite
+// Copyright (C) 2024  Igara Studio S.A.
+//
+// This program is distributed under the terms of
+// the End-User License Agreement for Aseprite.
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "app/ui/alpha_slider.h"
+#include "ui/message.h"
+
+#include <algorithm>
+
+using namespace ui;
+using namespace app::gen;
+
+namespace app {
+
+AlphaSlider::AlphaSlider(int value, Type type)
+  : ui::Slider(0, 255, value, this)
+  , m_type(type)
+{
+}
+
+void AlphaSlider::getSliderThemeInfo(int* min, int* max, int* value) const
+{
+  switch (getAlphaRange()) {
+    case AlphaRange::PERCENTAGE:
+      if (min) *min = 0;
+      if (max) *max = 100;
+      if (value) *value = std::round(((double)100)*((double)getValue())/((double)getMaxValue()));
+
+      return;
+    case AlphaRange::EIGHT_BIT:
+      return Slider::getSliderThemeInfo(min, max, value);
+  }
+}
+
+void AlphaSlider::updateValue(int value)
+{
+  if (getAlphaRange() == AlphaRange::PERCENTAGE)
+    value = std::round(((double)getMaxValue())*((double)value)/((double)100));
+
+  setValue(value);
+}
+
+std::string AlphaSlider::onGetTextFromValue(int value)
+{
+  char buf[128];
+  const char *format = "%d";
+  if (getAlphaRange() == AlphaRange::PERCENTAGE)
+      format = "%d%%";
+
+  std::snprintf(buf, sizeof(buf), format, value);
+  return buf;
+}
+
+int AlphaSlider::onGetValueFromText(const std::string& text)
+{
+  std::string str = text;
+  if (getAlphaRange() == AlphaRange::PERCENTAGE)
+      str.erase(std::remove(str.begin(), str.end(), '%'), str.end());
+
+  return std::strtol(str.c_str(), nullptr, 10);
+}
+
+}  // namespace app
diff --git a/src/app/ui/alpha_slider.h b/src/app/ui/alpha_slider.h
new file mode 100644
index 000000000..06edc9e11
--- /dev/null
+++ b/src/app/ui/alpha_slider.h
@@ -0,0 +1,42 @@
+// Aseprite
+// Copyright (C) 2024  Igara Studio S.A.
+//
+// This program is distributed under the terms of
+// the End-User License Agreement for Aseprite.
+
+#ifndef APP_UI_ALPHA_SLIDER_H_INCLUDED
+#define APP_UI_ALPHA_SLIDER_H_INCLUDED
+#pragma once
+
+#include "app/pref/preferences.h"
+#include "ui/slider.h"
+
+namespace app {
+
+class AlphaSlider : public ui::Slider,
+                    ui::SliderDelegate
+{
+public:
+  enum Type {ALPHA, OPACITY};
+
+  AlphaSlider(int value, Type type);
+
+  void getSliderThemeInfo(int* min, int* max, int* value) const override;
+  void updateValue(int value) override;
+
+  app::gen::AlphaRange getAlphaRange() const {
+    return (m_type == ALPHA ? Preferences::instance().range.alpha()
+                            : Preferences::instance().range.opacity());
+  }
+
+private:
+  // ui::SliderDelegate impl
+  std::string onGetTextFromValue(int value) override;
+  int onGetValueFromText(const std::string& text) override;
+
+  Type m_type;
+};
+
+}
+
+#endif
diff --git a/src/app/widget_loader.cpp b/src/app/widget_loader.cpp
index 957d3c5fd..50c1b1718 100644
--- a/src/app/widget_loader.cpp
+++ b/src/app/widget_loader.cpp
@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2019-2023  Igara Studio S.A.
+// Copyright (C) 2019-2024  Igara Studio S.A.
 // Copyright (C) 2001-2018  David Capello
 //
 // This program is distributed under the terms of
@@ -17,6 +17,7 @@
 #include "app/i18n/strings.h"
 #include "app/modules/gui.h"
 #include "app/resource_finder.h"
+#include "app/ui/alpha_slider.h"
 #include "app/ui/button_set.h"
 #include "app/ui/color_button.h"
 #include "app/ui/drop_down_button.h"
@@ -405,6 +406,13 @@ Widget* WidgetLoader::convertXmlElementToWidget(const TiXmlElement* elem, Widget
     widget = new Slider(min_value, max_value, min_value);
     static_cast<Slider*>(widget)->setReadOnly(readonly);
   }
+  else if (elem_name == "alphaslider" || elem_name == "opacityslider") {
+    const bool readonly = bool_attr(elem, "readonly", false);
+    widget = new AlphaSlider(0, (elem_name == "alphaslider"
+                                 ? AlphaSlider::Type::ALPHA
+                                 : AlphaSlider::Type::OPACITY));
+    static_cast<AlphaSlider*>(widget)->setReadOnly(readonly);
+  }
   else if (elem_name == "textbox") {
     const char* text = (elem->GetText() ? elem->GetText(): "");
     bool wordwrap = bool_attr(elem, "wordwrap", false);
diff --git a/src/gen/ui_class.cpp b/src/gen/ui_class.cpp
index c693cb268..6c16aae2e 100644
--- a/src/gen/ui_class.cpp
+++ b/src/gen/ui_class.cpp
@@ -1,5 +1,5 @@
 // Aseprite Code Generator
-// Copyright (c) 2021-2023 Igara Studio S.A.
+// Copyright (c) 2021-2024 Igara Studio S.A.
 // Copyright (c) 2014-2018 David Capello
 //
 // This file is released under the terms of the MIT license.
@@ -157,6 +157,9 @@ static Item convert_to_item(TiXmlElement* elem)
   if (name == "slider")
     return item.typeIncl("ui::Slider",
                          "ui/slider.h");
+  if (name == "alphaslider" || name == "opacityslider")
+    return item.typeIncl("app::AlphaSlider",
+                         "app/ui/alpha_slider.h");
   if (name == "splitter")
     return item.typeIncl("ui::Splitter",
                          "ui/splitter.h");
diff --git a/src/ui/slider.cpp b/src/ui/slider.cpp
index 5dbe1d4e9..1f178f7cd 100644
--- a/src/ui/slider.cpp
+++ b/src/ui/slider.cpp
@@ -1,5 +1,5 @@
 // Aseprite UI Library
-// Copyright (C) 2019-2022  Igara Studio S.A.
+// Copyright (C) 2019-2024  Igara Studio S.A.
 // Copyright (C) 2001-2016  David Capello
 //
 // This file is released under the terms of the MIT license.
@@ -24,9 +24,9 @@
 
 namespace ui {
 
-static int slider_press_x;
-static int slider_press_value;
-static bool slider_press_left;
+int Slider::slider_press_x;
+int Slider::slider_press_value;
+bool Slider::slider_press_left;
 
 Slider::Slider(int min, int max, int value, SliderDelegate* delegate)
   : Widget(kSliderWidget)
@@ -68,6 +68,11 @@ void Slider::getSliderThemeInfo(int* min, int* max, int* value) const
   if (value) *value = m_value;
 }
 
+void Slider::updateValue(int value)
+{
+  setValue(value);
+}
+
 std::string Slider::convertValueToText(int value) const
 {
   if (m_delegate)
@@ -106,9 +111,11 @@ bool Slider::onProcessMessage(Message* msg)
       captureMouse();
 
       {
+        int value;
+        getSliderThemeInfo(nullptr, nullptr, &value);
         gfx::Point mousePos = static_cast<MouseMessage*>(msg)->position();
         slider_press_x = mousePos.x;
-        slider_press_value = m_value;
+        slider_press_value = value;
         slider_press_left = static_cast<MouseMessage*>(msg)->left();
       }
 
@@ -118,27 +125,33 @@ bool Slider::onProcessMessage(Message* msg)
 
     case kMouseMoveMessage:
       if (hasCapture()) {
-        int value, accuracy, range;
+        int min, max, value, range;
         gfx::Rect rc = childrenBounds();
         gfx::Point mousePos = static_cast<MouseMessage*>(msg)->positionForDisplay(display());
 
-        range = m_max - m_min + 1;
+        getSliderThemeInfo(&min, &max, &value);
+
+        range =  max - min + 1;
 
         // With left click
         if (slider_press_left) {
-          value = m_min + range * (mousePos.x - rc.x) / rc.w;
+          value = min + range * (mousePos.x - rc.x) / rc.w;
         }
         // With right click
         else {
-          accuracy = std::clamp(rc.w / range, 1, rc.w);
+          int w = rc.w;
+          if (rc.w == 0 || range > rc.w) {
+            w = 1;
+            range = 1;
+          }
 
           value = slider_press_value +
-            (mousePos.x - slider_press_x) / accuracy;
+            (mousePos.x - slider_press_x) * range / w;
         }
 
-        value = std::clamp(value, m_min, m_max);
-        if (m_value != value) {
-          setValue(value);
+        value = std::clamp(value, min, max);
+        if (getValue() != value) {
+          updateValue(value);
           onChange();
         }
 
@@ -165,22 +178,24 @@ bool Slider::onProcessMessage(Message* msg)
 
     case kKeyDownMessage:
       if (hasFocus() && !isReadOnly()) {
-        int value = m_value;
+        int min, max, value, oldValue;
+        getSliderThemeInfo(&min, &max, &value);
+        oldValue = value;
 
         switch (static_cast<KeyMessage*>(msg)->scancode()) {
           case kKeyLeft:     --value; break;
           case kKeyRight:    ++value; break;
-          case kKeyPageDown: value -= (m_max-m_min+1)/4; break;
-          case kKeyPageUp:   value += (m_max-m_min+1)/4; break;
-          case kKeyHome:     value = m_min; break;
-          case kKeyEnd:      value = m_max; break;
+          case kKeyPageDown: value -= (max-min+1)/4; break;
+          case kKeyPageUp:   value += (max-min+1)/4; break;
+          case kKeyHome:     value = min; break;
+          case kKeyEnd:      value = max; break;
           default:
             goto not_used;
         }
 
-        value = std::clamp(value, m_min, m_max);
-        if (m_value != value) {
-          setValue(value);
+        value = std::clamp(value, min, max);
+        if (oldValue != value) {
+          updateValue(value);
           onChange();
         }
 
@@ -197,7 +212,7 @@ bool Slider::onProcessMessage(Message* msg)
         value = std::clamp(value, m_min, m_max);
 
         if (m_value != value) {
-          this->setValue(value);
+          setValue(value);
           onChange();
         }
         return true;
diff --git a/src/ui/slider.h b/src/ui/slider.h
index 35c1a5b31..5f986bf83 100644
--- a/src/ui/slider.h
+++ b/src/ui/slider.h
@@ -1,5 +1,5 @@
 // Aseprite UI Library
-// Copyright (C) 2020  Igara Studio S.A.
+// Copyright (C) 2020-2024  Igara Studio S.A.
 // Copyright (C) 2001-2016  David Capello
 //
 // This file is released under the terms of the MIT license.
@@ -35,7 +35,8 @@ namespace ui {
     bool isReadOnly() const { return m_readOnly; }
     void setReadOnly(bool readOnly) { m_readOnly = readOnly; }
 
-    void getSliderThemeInfo(int* min, int* max, int* value) const;
+    virtual void getSliderThemeInfo(int* min, int* max, int* value) const;
+    virtual void updateValue(int value);
 
     std::string convertValueToText(int value) const;
     int convertTextToValue(const std::string& text) const;
@@ -45,6 +46,10 @@ namespace ui {
     obs::signal<void()> SliderReleased;
 
   protected:
+    static int slider_press_x;
+    static int slider_press_value;
+    static bool slider_press_left;
+
     // Events
     bool onProcessMessage(Message* msg) override;
     void onPaint(PaintEvent& ev) override;