diff --git a/Libraries/LibGUI/Event.h b/Libraries/LibGUI/Event.h
index 1dd6dec569..b8dbe6d73e 100644
--- a/Libraries/LibGUI/Event.h
+++ b/Libraries/LibGUI/Event.h
@@ -111,7 +111,7 @@ public:
 
 class WMWindowStateChangedEvent : public WMEvent {
 public:
-    WMWindowStateChangedEvent(int client_id, int window_id, const StringView& title, const Gfx::Rect& rect, bool is_active, WindowType window_type, bool is_minimized, bool is_frameless)
+    WMWindowStateChangedEvent(int client_id, int window_id, const StringView& title, const Gfx::Rect& rect, bool is_active, WindowType window_type, bool is_minimized, bool is_frameless, int progress)
         : WMEvent(Event::Type::WM_WindowStateChanged, client_id, window_id)
         , m_title(title)
         , m_rect(rect)
@@ -119,6 +119,7 @@ public:
         , m_active(is_active)
         , m_minimized(is_minimized)
         , m_frameless(is_frameless)
+        , m_progress(progress)
     {
     }
 
@@ -128,6 +129,7 @@ public:
     WindowType window_type() const { return m_window_type; }
     bool is_minimized() const { return m_minimized; }
     bool is_frameless() const { return m_frameless; }
+    int progress() const { return m_progress; }
 
 private:
     String m_title;
@@ -136,6 +138,7 @@ private:
     bool m_active;
     bool m_minimized;
     bool m_frameless;
+    int m_progress;
 };
 
 class WMWindowRectChangedEvent : public WMEvent {
diff --git a/Libraries/LibGUI/Window.cpp b/Libraries/LibGUI/Window.cpp
index 805c8353f0..91d435c68b 100644
--- a/Libraries/LibGUI/Window.cpp
+++ b/Libraries/LibGUI/Window.cpp
@@ -779,4 +779,10 @@ void Window::did_remove_widget(Badge<Widget>, Widget& widget)
         m_automatic_cursor_tracking_widget = nullptr;
 }
 
+void Window::set_progress(int progress)
+{
+    ASSERT(m_window_id);
+    WindowServerConnection::the().post_message(Messages::WindowServer::SetWindowProgress(m_window_id, progress));
+}
+
 }
diff --git a/Libraries/LibGUI/Window.h b/Libraries/LibGUI/Window.h
index c2ca561f60..f8d8428a64 100644
--- a/Libraries/LibGUI/Window.h
+++ b/Libraries/LibGUI/Window.h
@@ -188,6 +188,8 @@ public:
 
     Window* find_parent_window();
 
+    void set_progress(int);
+
 protected:
     Window(Core::Object* parent = nullptr);
     virtual void wm_event(WMEvent&);
diff --git a/Libraries/LibGUI/WindowServerConnection.cpp b/Libraries/LibGUI/WindowServerConnection.cpp
index 38ef7f0f8b..afa94e5768 100644
--- a/Libraries/LibGUI/WindowServerConnection.cpp
+++ b/Libraries/LibGUI/WindowServerConnection.cpp
@@ -266,7 +266,7 @@ void WindowServerConnection::handle(const Messages::WindowClient::MenuItemActiva
 void WindowServerConnection::handle(const Messages::WindowClient::WM_WindowStateChanged& message)
 {
     if (auto* window = Window::from_window_id(message.wm_id()))
-        Core::EventLoop::current().post_event(*window, make<WMWindowStateChangedEvent>(message.client_id(), message.window_id(), message.title(), message.rect(), message.is_active(), static_cast<WindowType>(message.window_type()), message.is_minimized(), message.is_frameless()));
+        Core::EventLoop::current().post_event(*window, make<WMWindowStateChangedEvent>(message.client_id(), message.window_id(), message.title(), message.rect(), message.is_active(), static_cast<WindowType>(message.window_type()), message.is_minimized(), message.is_frameless(), message.progress()));
 }
 
 void WindowServerConnection::handle(const Messages::WindowClient::WM_WindowRectChanged& message)
diff --git a/Services/WindowServer/ClientConnection.cpp b/Services/WindowServer/ClientConnection.cpp
index e476124b9d..51d645d578 100644
--- a/Services/WindowServer/ClientConnection.cpp
+++ b/Services/WindowServer/ClientConnection.cpp
@@ -810,4 +810,14 @@ void ClientConnection::notify_display_link(Badge<Compositor>)
     post_message(Messages::WindowClient::DisplayLinkNotification());
 }
 
+void ClientConnection::handle(const Messages::WindowServer::SetWindowProgress& message)
+{
+    auto it = m_windows.find(message.window_id());
+    if (it == m_windows.end()) {
+        did_misbehave("SetWindowProgress with bad window ID");
+        return;
+    }
+    it->value->set_progress(message.progress());
+}
+
 }
diff --git a/Services/WindowServer/ClientConnection.h b/Services/WindowServer/ClientConnection.h
index 3ae22199b2..a871b636e8 100644
--- a/Services/WindowServer/ClientConnection.h
+++ b/Services/WindowServer/ClientConnection.h
@@ -133,6 +133,7 @@ private:
     virtual OwnPtr<Messages::WindowServer::SetWindowBaseSizeAndSizeIncrementResponse> handle(const Messages::WindowServer::SetWindowBaseSizeAndSizeIncrement&) override;
     virtual void handle(const Messages::WindowServer::EnableDisplayLink&) override;
     virtual void handle(const Messages::WindowServer::DisableDisplayLink&) override;
+    virtual void handle(const Messages::WindowServer::SetWindowProgress&) override;
 
     Window* window_from_id(i32 window_id);
 
diff --git a/Services/WindowServer/Window.cpp b/Services/WindowServer/Window.cpp
index 874f518ef5..e816935da8 100644
--- a/Services/WindowServer/Window.cpp
+++ b/Services/WindowServer/Window.cpp
@@ -537,4 +537,13 @@ void Window::set_parent_window(Window& parent_window)
     parent_window.add_child_window(*this);
 }
 
+void Window::set_progress(int progress)
+{
+    if (m_progress == progress)
+        return;
+
+    m_progress = progress;
+    WindowManager::the().notify_progress_changed(*this);
+}
+
 }
diff --git a/Services/WindowServer/Window.h b/Services/WindowServer/Window.h
index 09856c96dd..b931b93955 100644
--- a/Services/WindowServer/Window.h
+++ b/Services/WindowServer/Window.h
@@ -232,6 +232,9 @@ public:
     void set_frameless(bool frameless) { m_frameless = frameless; }
     bool is_frameless() const { return m_frameless; }
 
+    int progress() const { return m_progress; }
+    void set_progress(int);
+
 private:
     void handle_mouse_event(const MouseEvent&);
     void update_menu_item_text(PopupMenuItem item);
@@ -281,6 +284,7 @@ private:
     MenuItem* m_window_menu_minimize_item { nullptr };
     MenuItem* m_window_menu_maximize_item { nullptr };
     int m_minimize_animation_step { -1 };
+    int m_progress { -1 };
 };
 
 }
diff --git a/Services/WindowServer/WindowClient.ipc b/Services/WindowServer/WindowClient.ipc
index 37e369de7e..ddcdcb6cf7 100644
--- a/Services/WindowServer/WindowClient.ipc
+++ b/Services/WindowServer/WindowClient.ipc
@@ -21,7 +21,7 @@ endpoint WindowClient = 4
     ScreenRectChanged(Gfx::Rect rect) =|
 
     WM_WindowRemoved(i32 wm_id, i32 client_id, i32 window_id) =|
-    WM_WindowStateChanged(i32 wm_id, i32 client_id, i32 window_id, bool is_active, bool is_minimized, bool is_frameless, i32 window_type, [UTF8] String title, Gfx::Rect rect) =|
+    WM_WindowStateChanged(i32 wm_id, i32 client_id, i32 window_id, bool is_active, bool is_minimized, bool is_frameless, i32 window_type, [UTF8] String title, Gfx::Rect rect, i32 progress) =|
     WM_WindowIconBitmapChanged(i32 wm_id, i32 client_id, i32 window_id, i32 icon_buffer_id, Gfx::Size icon_size) =|
     WM_WindowRectChanged(i32 wm_id, i32 client_id, i32 window_id, Gfx::Rect rect) =|
 
diff --git a/Services/WindowServer/WindowManager.cpp b/Services/WindowServer/WindowManager.cpp
index 977f892d7d..5d900fd930 100644
--- a/Services/WindowServer/WindowManager.cpp
+++ b/Services/WindowServer/WindowManager.cpp
@@ -253,7 +253,7 @@ void WindowManager::tell_wm_listener_about_window(Window& listener, Window& wind
         return;
     if (window.is_internal())
         return;
-    listener.client()->post_message(Messages::WindowClient::WM_WindowStateChanged(listener.window_id(), window.client_id(), window.window_id(), window.is_active(), window.is_minimized(), window.is_frameless(), (i32)window.type(), window.title(), window.rect()));
+    listener.client()->post_message(Messages::WindowClient::WM_WindowStateChanged(listener.window_id(), window.client_id(), window.window_id(), window.is_active(), window.is_minimized(), window.is_frameless(), (i32)window.type(), window.title(), window.rect(), window.progress()));
 }
 
 void WindowManager::tell_wm_listener_about_window_rect(Window& listener, Window& window)
@@ -359,6 +359,11 @@ void WindowManager::notify_occlusion_state_changed(Window& window)
         window.client()->post_message(Messages::WindowClient::WindowStateChanged(window.window_id(), window.is_minimized(), window.is_occluded()));
 }
 
+void WindowManager::notify_progress_changed(Window& window)
+{
+    tell_wm_listeners_window_state_changed(window);
+}
+
 void WindowManager::pick_new_active_window()
 {
     bool new_window_picked = false;
diff --git a/Services/WindowServer/WindowManager.h b/Services/WindowServer/WindowManager.h
index a3bb68d084..14688e0a26 100644
--- a/Services/WindowServer/WindowManager.h
+++ b/Services/WindowServer/WindowManager.h
@@ -92,6 +92,7 @@ public:
     void notify_minimization_state_changed(Window&);
     void notify_opacity_changed(Window&);
     void notify_occlusion_state_changed(Window&);
+    void notify_progress_changed(Window&);
     void notify_client_changed_app_menubar(ClientConnection&);
 
     Gfx::Rect maximized_window_rect(const Window&) const;
diff --git a/Services/WindowServer/WindowServer.ipc b/Services/WindowServer/WindowServer.ipc
index dbd3c06957..3b08a7dd83 100644
--- a/Services/WindowServer/WindowServer.ipc
+++ b/Services/WindowServer/WindowServer.ipc
@@ -49,6 +49,8 @@ endpoint WindowServer = 2
     SetWindowTitle(i32 window_id, [UTF8] String title) => ()
     GetWindowTitle(i32 window_id) => ([UTF8] String title)
 
+    SetWindowProgress(i32 window_id, i32 progress) =|
+
     SetWindowRect(i32 window_id, Gfx::Rect rect) => (Gfx::Rect rect)
     GetWindowRect(i32 window_id) => (Gfx::Rect rect)