WindowServer: Make various function arguments const.

13 files changed, 124 insertions, 124 deletions

diff --git a/Servers/WindowServer/WSClientConnection.cpp b/Servers/WindowServer/WSClientConnection.cpp
index 3ca579d96f..3aa1dc95d2 100644
--- a/Servers/WindowServer/WSClientConnection.cpp
+++ b/Servers/WindowServer/WSClientConnection.cpp
@@ -83,22 +83,22 @@ void WSClientConnection::post_message(const WSAPI_ServerMessage& message)
     ASSERT(nwritten == sizeof(message));
 }
 
-void WSClientConnection::on_message(WSMessage& message)
+void WSClientConnection::on_message(const WSMessage& message)
 {
     if (message.is_client_request()) {
-        on_request(static_cast<WSAPIClientRequest&>(message));
+        on_request(static_cast<const WSAPIClientRequest&>(message));
         return;
     }
 
     if (message.type() == WSMessage::WM_ClientDisconnected) {
-        int client_id = static_cast<WSClientDisconnectedNotification&>(message).client_id();
+        int client_id = static_cast<const WSClientDisconnectedNotification&>(message).client_id();
         dbgprintf("WSClientConnection: Client disconnected: %d\n", client_id);
         delete this;
         return;
     }
 }
 
-void WSClientConnection::handle_request(WSAPICreateMenubarRequest&)
+void WSClientConnection::handle_request(const WSAPICreateMenubarRequest&)
 {
     int menubar_id = m_next_menubar_id++;
     auto menubar = make<WSMenuBar>(*this, menubar_id);
@@ -109,7 +109,7 @@ void WSClientConnection::handle_request(WSAPICreateMenubarRequest&)
     post_message(response);
 }
 
-void WSClientConnection::handle_request(WSAPIDestroyMenubarRequest& request)
+void WSClientConnection::handle_request(const WSAPIDestroyMenubarRequest& request)
 {
     int menubar_id = request.menubar_id();
     auto it = m_menubars.find(menubar_id);
@@ -126,7 +126,7 @@ void WSClientConnection::handle_request(WSAPIDestroyMenubarRequest& request)
     post_message(response);
 }
 
-void WSClientConnection::handle_request(WSAPICreateMenuRequest& request)
+void WSClientConnection::handle_request(const WSAPICreateMenuRequest& request)
 {
     int menu_id = m_next_menu_id++;
     auto menu = make<WSMenu>(this, menu_id, request.text());
@@ -137,9 +137,9 @@ void WSClientConnection::handle_request(WSAPICreateMenuRequest& request)
     post_message(response);
 }
 
-void WSClientConnection::handle_request(WSAPIDestroyMenuRequest& request)
+void WSClientConnection::handle_request(const WSAPIDestroyMenuRequest& request)
 {
-    int menu_id = static_cast<WSAPIDestroyMenuRequest&>(request).menu_id();
+    int menu_id = static_cast<const WSAPIDestroyMenuRequest&>(request).menu_id();
     auto it = m_menus.find(menu_id);
     if (it == m_menus.end()) {
         post_error("Bad menu ID");
@@ -154,7 +154,7 @@ void WSClientConnection::handle_request(WSAPIDestroyMenuRequest& request)
     post_message(response);
 }
 
-void WSClientConnection::handle_request(WSAPISetApplicationMenubarRequest& request)
+void WSClientConnection::handle_request(const WSAPISetApplicationMenubarRequest& request)
 {
     int menubar_id = request.menubar_id();
     auto it = m_menubars.find(menubar_id);
@@ -171,7 +171,7 @@ void WSClientConnection::handle_request(WSAPISetApplicationMenubarRequest& reque
     post_message(response);
 }
 
-void WSClientConnection::handle_request(WSAPIAddMenuToMenubarRequest& request)
+void WSClientConnection::handle_request(const WSAPIAddMenuToMenubarRequest& request)
 {
     int menubar_id = request.menubar_id();
     int menu_id = request.menu_id();
@@ -195,7 +195,7 @@ void WSClientConnection::handle_request(WSAPIAddMenuToMenubarRequest& request)
     post_message(response);
 }
 
-void WSClientConnection::handle_request(WSAPIAddMenuItemRequest& request)
+void WSClientConnection::handle_request(const WSAPIAddMenuItemRequest& request)
 {
     int menu_id = request.menu_id();
     unsigned identifier = request.identifier();
@@ -213,7 +213,7 @@ void WSClientConnection::handle_request(WSAPIAddMenuItemRequest& request)
     post_message(response);
 }
 
-void WSClientConnection::handle_request(WSAPIAddMenuSeparatorRequest& request)
+void WSClientConnection::handle_request(const WSAPIAddMenuSeparatorRequest& request)
 {
     int menu_id = request.menu_id();
     auto it = m_menus.find(menu_id);
@@ -229,7 +229,7 @@ void WSClientConnection::handle_request(WSAPIAddMenuSeparatorRequest& request)
     post_message(response);
 }
 
-void WSClientConnection::handle_request(WSAPISetWindowOpacityRequest& request)
+void WSClientConnection::handle_request(const WSAPISetWindowOpacityRequest& request)
 {
     int window_id = request.window_id();
     auto it = m_windows.find(window_id);
@@ -241,7 +241,7 @@ void WSClientConnection::handle_request(WSAPISetWindowOpacityRequest& request)
     window.set_opacity(request.opacity());
 }
 
-void WSClientConnection::handle_request(WSAPISetWallpaperRequest& request)
+void WSClientConnection::handle_request(const WSAPISetWallpaperRequest& request)
 {
     bool success = WSWindowManager::the().set_wallpaper(request.wallpaper());
     WSAPI_ServerMessage response;
@@ -250,7 +250,7 @@ void WSClientConnection::handle_request(WSAPISetWallpaperRequest& request)
     post_message(response);
 }
 
-void WSClientConnection::handle_request(WSAPIGetWallpaperRequest& request)
+void WSClientConnection::handle_request(const WSAPIGetWallpaperRequest&)
 {
     auto path = WSWindowManager::the().wallpaper_path();
     WSAPI_ServerMessage response;
@@ -261,7 +261,7 @@ void WSClientConnection::handle_request(WSAPIGetWallpaperRequest& request)
     post_message(response);
 }
 
-void WSClientConnection::handle_request(WSAPISetWindowTitleRequest& request)
+void WSClientConnection::handle_request(const WSAPISetWindowTitleRequest& request)
 {
     int window_id = request.window_id();
     auto it = m_windows.find(window_id);
@@ -273,7 +273,7 @@ void WSClientConnection::handle_request(WSAPISetWindowTitleRequest& request)
     window.set_title(request.title());
 }
 
-void WSClientConnection::handle_request(WSAPIGetWindowTitleRequest& request)
+void WSClientConnection::handle_request(const WSAPIGetWindowTitleRequest& request)
 {
     int window_id = request.window_id();
     auto it = m_windows.find(window_id);
@@ -291,7 +291,7 @@ void WSClientConnection::handle_request(WSAPIGetWindowTitleRequest& request)
     post_message(response);
 }
 
-void WSClientConnection::handle_request(WSAPISetWindowRectRequest& request)
+void WSClientConnection::handle_request(const WSAPISetWindowRectRequest& request)
 {
     int window_id = request.window_id();
     auto it = m_windows.find(window_id);
@@ -303,7 +303,7 @@ void WSClientConnection::handle_request(WSAPISetWindowRectRequest& request)
     window.set_rect(request.rect());
 }
 
-void WSClientConnection::handle_request(WSAPIGetWindowRectRequest& request)
+void WSClientConnection::handle_request(const WSAPIGetWindowRectRequest& request)
 {
     int window_id = request.window_id();
     auto it = m_windows.find(window_id);
@@ -319,7 +319,7 @@ void WSClientConnection::handle_request(WSAPIGetWindowRectRequest& request)
     post_message(response);
 }
 
-void WSClientConnection::handle_request(WSAPISetClipboardContentsRequest& request)
+void WSClientConnection::handle_request(const WSAPISetClipboardContentsRequest& request)
 {
     auto shared_buffer = SharedBuffer::create_from_shared_buffer_id(request.shared_buffer_id());
     if (!shared_buffer) {
@@ -333,7 +333,7 @@ void WSClientConnection::handle_request(WSAPISetClipboardContentsRequest& reques
     post_message(response);
 }
 
-void WSClientConnection::handle_request(WSAPIGetClipboardContentsRequest&)
+void WSClientConnection::handle_request(const WSAPIGetClipboardContentsRequest&)
 {
     WSAPI_ServerMessage response;
     response.type = WSAPI_ServerMessage::Type::DidGetClipboardContents;
@@ -357,7 +357,7 @@ void WSClientConnection::handle_request(WSAPIGetClipboardContentsRequest&)
     post_message(response);
 }
 
-void WSClientConnection::handle_request(WSAPICreateWindowRequest& request)
+void WSClientConnection::handle_request(const WSAPICreateWindowRequest& request)
 {
     int window_id = m_next_window_id++;
     auto window = make<WSWindow>(*this, window_id, request.is_modal());
@@ -376,7 +376,7 @@ void WSClientConnection::handle_request(WSAPICreateWindowRequest& request)
     post_message(response);
 }
 
-void WSClientConnection::handle_request(WSAPIDestroyWindowRequest& request)
+void WSClientConnection::handle_request(const WSAPIDestroyWindowRequest& request)
 {
     int window_id = request.window_id();
     auto it = m_windows.find(window_id);
@@ -389,7 +389,7 @@ void WSClientConnection::handle_request(WSAPIDestroyWindowRequest& request)
     m_windows.remove(it);
 }
 
-void WSClientConnection::handle_request(WSAPIInvalidateRectRequest& request)
+void WSClientConnection::handle_request(const WSAPIInvalidateRectRequest& request)
 {
     int window_id = request.window_id();
     auto it = m_windows.find(window_id);
@@ -406,7 +406,7 @@ void WSClientConnection::handle_request(WSAPIInvalidateRectRequest& request)
     post_message(response);
 }
 
-void WSClientConnection::handle_request(WSAPIDidFinishPaintingNotification& request)
+void WSClientConnection::handle_request(const WSAPIDidFinishPaintingNotification& request)
 {
     int window_id = request.window_id();
     auto it = m_windows.find(window_id);
@@ -425,7 +425,7 @@ void WSClientConnection::handle_request(WSAPIDidFinishPaintingNotification& requ
     WSWindowManager::the().invalidate(window, request.rect());
 }
 
-void WSClientConnection::handle_request(WSAPIGetWindowBackingStoreRequest& request)
+void WSClientConnection::handle_request(const WSAPIGetWindowBackingStoreRequest& request)
 {
     int window_id = request.window_id();
     auto it = m_windows.find(window_id);
@@ -447,7 +447,7 @@ void WSClientConnection::handle_request(WSAPIGetWindowBackingStoreRequest& reque
     post_message(response);
 }
 
-void WSClientConnection::handle_request(WSAPISetWindowBackingStoreRequest& request)
+void WSClientConnection::handle_request(const WSAPISetWindowBackingStoreRequest& request)
 {
     int window_id = request.window_id();
     auto it = m_windows.find(window_id);
@@ -479,7 +479,7 @@ void WSClientConnection::handle_request(WSAPISetWindowBackingStoreRequest& reque
     post_message(response);
 }
 
-void WSClientConnection::handle_request(WSAPISetGlobalCursorTrackingRequest& request)
+void WSClientConnection::handle_request(const WSAPISetGlobalCursorTrackingRequest& request)
 {
     int window_id = request.window_id();
     auto it = m_windows.find(window_id);
@@ -491,7 +491,7 @@ void WSClientConnection::handle_request(WSAPISetGlobalCursorTrackingRequest& req
     window.set_global_cursor_tracking_enabled(request.value());
 }
 
-void WSClientConnection::handle_request(WSAPISetWindowOverrideCursorRequest& request)
+void WSClientConnection::handle_request(const WSAPISetWindowOverrideCursorRequest& request)
 {
     int window_id = request.window_id();
     auto it = m_windows.find(window_id);
@@ -503,59 +503,59 @@ void WSClientConnection::handle_request(WSAPISetWindowOverrideCursorRequest& req
     window.set_override_cursor(WSCursor::create(request.cursor()));
 }
 
-void WSClientConnection::on_request(WSAPIClientRequest& request)
+void WSClientConnection::on_request(const WSAPIClientRequest& request)
 {
     switch (request.type()) {
     case WSMessage::APICreateMenubarRequest:
-        return handle_request(static_cast<WSAPICreateMenubarRequest&>(request));
+        return handle_request(static_cast<const WSAPICreateMenubarRequest&>(request));
     case WSMessage::APIDestroyMenubarRequest:
-        return handle_request(static_cast<WSAPIDestroyMenubarRequest&>(request));
+        return handle_request(static_cast<const WSAPIDestroyMenubarRequest&>(request));
     case WSMessage::APICreateMenuRequest:
-        return handle_request(static_cast<WSAPICreateMenuRequest&>(request));
+        return handle_request(static_cast<const WSAPICreateMenuRequest&>(request));
     case WSMessage::APIDestroyMenuRequest:
-        return handle_request(static_cast<WSAPIDestroyMenuRequest&>(request));
+        return handle_request(static_cast<const WSAPIDestroyMenuRequest&>(request));
     case WSMessage::APISetApplicationMenubarRequest:
-        return handle_request(static_cast<WSAPISetApplicationMenubarRequest&>(request));
+        return handle_request(static_cast<const WSAPISetApplicationMenubarRequest&>(request));
     case WSMessage::APIAddMenuToMenubarRequest:
-        return handle_request(static_cast<WSAPIAddMenuToMenubarRequest&>(request));
+        return handle_request(static_cast<const WSAPIAddMenuToMenubarRequest&>(request));
     case WSMessage::APIAddMenuItemRequest:
-        return handle_request(static_cast<WSAPIAddMenuItemRequest&>(request));
+        return handle_request(static_cast<const WSAPIAddMenuItemRequest&>(request));
     case WSMessage::APIAddMenuSeparatorRequest:
-        return handle_request(static_cast<WSAPIAddMenuSeparatorRequest&>(request));
+        return handle_request(static_cast<const WSAPIAddMenuSeparatorRequest&>(request));
     case WSMessage::APISetWindowTitleRequest:
-        return handle_request(static_cast<WSAPISetWindowTitleRequest&>(request));
+        return handle_request(static_cast<const WSAPISetWindowTitleRequest&>(request));
     case WSMessage::APIGetWindowTitleRequest:
-        return handle_request(static_cast<WSAPIGetWindowTitleRequest&>(request));
+        return handle_request(static_cast<const WSAPIGetWindowTitleRequest&>(request));
     case WSMessage::APISetWindowRectRequest:
-        return handle_request(static_cast<WSAPISetWindowRectRequest&>(request));
+        return handle_request(static_cast<const WSAPISetWindowRectRequest&>(request));
     case WSMessage::APIGetWindowRectRequest:
-        return handle_request(static_cast<WSAPIGetWindowRectRequest&>(request));
+        return handle_request(static_cast<const WSAPIGetWindowRectRequest&>(request));
     case WSMessage::APISetClipboardContentsRequest:
-        return handle_request(static_cast<WSAPISetClipboardContentsRequest&>(request));
+        return handle_request(static_cast<const WSAPISetClipboardContentsRequest&>(request));
     case WSMessage::APIGetClipboardContentsRequest:
-        return handle_request(static_cast<WSAPIGetClipboardContentsRequest&>(request));
+        return handle_request(static_cast<const WSAPIGetClipboardContentsRequest&>(request));
     case WSMessage::APICreateWindowRequest:
-        return handle_request(static_cast<WSAPICreateWindowRequest&>(request));
+        return handle_request(static_cast<const WSAPICreateWindowRequest&>(request));
     case WSMessage::APIDestroyWindowRequest:
-        return handle_request(static_cast<WSAPIDestroyWindowRequest&>(request));
+        return handle_request(static_cast<const WSAPIDestroyWindowRequest&>(request));
     case WSMessage::APIInvalidateRectRequest:
-        return handle_request(static_cast<WSAPIInvalidateRectRequest&>(request));
+        return handle_request(static_cast<const WSAPIInvalidateRectRequest&>(request));
     case WSMessage::APIDidFinishPaintingNotification:
-        return handle_request(static_cast<WSAPIDidFinishPaintingNotification&>(request));
+        return handle_request(static_cast<const WSAPIDidFinishPaintingNotification&>(request));
     case WSMessage::APIGetWindowBackingStoreRequest:
-        return handle_request(static_cast<WSAPIGetWindowBackingStoreRequest&>(request));
+        return handle_request(static_cast<const WSAPIGetWindowBackingStoreRequest&>(request));
     case WSMessage::APISetGlobalCursorTrackingRequest:
-        return handle_request(static_cast<WSAPISetGlobalCursorTrackingRequest&>(request));
+        return handle_request(static_cast<const WSAPISetGlobalCursorTrackingRequest&>(request));
     case WSMessage::APISetWindowOpacityRequest:
-        return handle_request(static_cast<WSAPISetWindowOpacityRequest&>(request));
+        return handle_request(static_cast<const WSAPISetWindowOpacityRequest&>(request));
     case WSMessage::APISetWindowBackingStoreRequest:
-        return handle_request(static_cast<WSAPISetWindowBackingStoreRequest&>(request));
+        return handle_request(static_cast<const WSAPISetWindowBackingStoreRequest&>(request));
     case WSMessage::APISetWallpaperRequest:
-        return handle_request(static_cast<WSAPISetWallpaperRequest&>(request));
+        return handle_request(static_cast<const WSAPISetWallpaperRequest&>(request));
     case WSMessage::APIGetWallpaperRequest:
-        return handle_request(static_cast<WSAPIGetWallpaperRequest&>(request));
+        return handle_request(static_cast<const WSAPIGetWallpaperRequest&>(request));
     case WSMessage::APISetWindowOverrideCursorRequest:
-        return handle_request(static_cast<WSAPISetWindowOverrideCursorRequest&>(request));
+        return handle_request(static_cast<const WSAPISetWindowOverrideCursorRequest&>(request));
     default:
         break;
     }
diff --git a/Servers/WindowServer/WSClientConnection.h b/Servers/WindowServer/WSClientConnection.h
index f596ac59e1..e636efe5b2 100644
--- a/Servers/WindowServer/WSClientConnection.h
+++ b/Servers/WindowServer/WSClientConnection.h
@@ -37,34 +37,34 @@ public:
     template<typename Callback> void for_each_window(Callback);
 
 private:
-    virtual void on_message(WSMessage&) override;
-
-    void on_request(WSAPIClientRequest&);
-    void handle_request(WSAPICreateMenubarRequest&);
-    void handle_request(WSAPIDestroyMenubarRequest&);
-    void handle_request(WSAPICreateMenuRequest&);
-    void handle_request(WSAPIDestroyMenuRequest&);
-    void handle_request(WSAPISetApplicationMenubarRequest&);
-    void handle_request(WSAPIAddMenuToMenubarRequest&);
-    void handle_request(WSAPIAddMenuItemRequest&);
-    void handle_request(WSAPIAddMenuSeparatorRequest&);
-    void handle_request(WSAPISetWindowTitleRequest&);
-    void handle_request(WSAPIGetWindowTitleRequest&);
-    void handle_request(WSAPISetWindowRectRequest&);
-    void handle_request(WSAPIGetWindowRectRequest&);
-    void handle_request(WSAPISetClipboardContentsRequest&);
-    void handle_request(WSAPIGetClipboardContentsRequest&);
-    void handle_request(WSAPICreateWindowRequest&);
-    void handle_request(WSAPIDestroyWindowRequest&);
-    void handle_request(WSAPIInvalidateRectRequest&);
-    void handle_request(WSAPIDidFinishPaintingNotification&);
-    void handle_request(WSAPIGetWindowBackingStoreRequest&);
-    void handle_request(WSAPISetWindowBackingStoreRequest&);
-    void handle_request(WSAPISetGlobalCursorTrackingRequest&);
-    void handle_request(WSAPISetWindowOpacityRequest&);
-    void handle_request(WSAPISetWallpaperRequest&);
-    void handle_request(WSAPIGetWallpaperRequest&);
-    void handle_request(WSAPISetWindowOverrideCursorRequest&);
+    virtual void on_message(const WSMessage&) override;
+
+    void on_request(const WSAPIClientRequest&);
+    void handle_request(const WSAPICreateMenubarRequest&);
+    void handle_request(const WSAPIDestroyMenubarRequest&);
+    void handle_request(const WSAPICreateMenuRequest&);
+    void handle_request(const WSAPIDestroyMenuRequest&);
+    void handle_request(const WSAPISetApplicationMenubarRequest&);
+    void handle_request(const WSAPIAddMenuToMenubarRequest&);
+    void handle_request(const WSAPIAddMenuItemRequest&);
+    void handle_request(const WSAPIAddMenuSeparatorRequest&);
+    void handle_request(const WSAPISetWindowTitleRequest&);
+    void handle_request(const WSAPIGetWindowTitleRequest&);
+    void handle_request(const WSAPISetWindowRectRequest&);
+    void handle_request(const WSAPIGetWindowRectRequest&);
+    void handle_request(const WSAPISetClipboardContentsRequest&);
+    void handle_request(const WSAPIGetClipboardContentsRequest&);
+    void handle_request(const WSAPICreateWindowRequest&);
+    void handle_request(const WSAPIDestroyWindowRequest&);
+    void handle_request(const WSAPIInvalidateRectRequest&);
+    void handle_request(const WSAPIDidFinishPaintingNotification&);
+    void handle_request(const WSAPIGetWindowBackingStoreRequest&);
+    void handle_request(const WSAPISetWindowBackingStoreRequest&);
+    void handle_request(const WSAPISetGlobalCursorTrackingRequest&);
+    void handle_request(const WSAPISetWindowOpacityRequest&);
+    void handle_request(const WSAPISetWallpaperRequest&);
+    void handle_request(const WSAPIGetWallpaperRequest&);
+    void handle_request(const WSAPISetWindowOverrideCursorRequest&);
 
     void post_error(const String&);
 
diff --git a/Servers/WindowServer/WSClipboard.cpp b/Servers/WindowServer/WSClipboard.cpp
index 1a7f8f2ea1..7e54b168c8 100644
--- a/Servers/WindowServer/WSClipboard.cpp
+++ b/Servers/WindowServer/WSClipboard.cpp
@@ -16,7 +16,7 @@ WSClipboard::~WSClipboard()
 {
 }
 
-void WSClipboard::on_message(WSMessage&)
+void WSClipboard::on_message(const WSMessage&)
 {
 }
 
diff --git a/Servers/WindowServer/WSClipboard.h b/Servers/WindowServer/WSClipboard.h
index 6c29bb8cd8..2d22beb6f3 100644
--- a/Servers/WindowServer/WSClipboard.h
+++ b/Servers/WindowServer/WSClipboard.h
@@ -22,7 +22,7 @@ public:
 
 private:
     WSClipboard();
-    virtual void on_message(WSMessage&) override;
+    virtual void on_message(const WSMessage&) override;
 
     RetainPtr<SharedBuffer> m_shared_buffer;
     int m_contents_size { 0 };
diff --git a/Servers/WindowServer/WSMenu.cpp b/Servers/WindowServer/WSMenu.cpp
index b8b457122f..02eeaa7723 100644
--- a/Servers/WindowServer/WSMenu.cpp
+++ b/Servers/WindowServer/WSMenu.cpp
@@ -107,11 +107,11 @@ void WSMenu::draw()
     }
 }
 
-void WSMenu::on_message(WSMessage& message)
+void WSMenu::on_message(const WSMessage& message)
 {
     ASSERT(menu_window());
     if (message.type() == WSMessage::MouseMove) {
-        auto* item = item_at(static_cast<WSMouseEvent&>(message).position());
+        auto* item = item_at(static_cast<const WSMouseEvent&>(message).position());
         if (!item || m_hovered_item == item)
             return;
         m_hovered_item = item;
diff --git a/Servers/WindowServer/WSMenu.h b/Servers/WindowServer/WSMenu.h
index e7e6c34ef0..03315358a8 100644
--- a/Servers/WindowServer/WSMenu.h
+++ b/Servers/WindowServer/WSMenu.h
@@ -73,7 +73,7 @@ public:
     void close();
 
 private:
-    virtual void on_message(WSMessage&) override;
+    virtual void on_message(const WSMessage&) override;
 
     int padding_between_text_and_shortcut() const { return 50; }
     void did_activate(WSMenuItem&);
diff --git a/Servers/WindowServer/WSMessageReceiver.h b/Servers/WindowServer/WSMessageReceiver.h
index 97ee114c8c..eaf8933846 100644
--- a/Servers/WindowServer/WSMessageReceiver.h
+++ b/Servers/WindowServer/WSMessageReceiver.h
@@ -9,5 +9,5 @@ public:
     WSMessageReceiver();
     virtual ~WSMessageReceiver();
 
-    virtual void on_message(WSMessage&) = 0;
+    virtual void on_message(const WSMessage&) = 0;
 };
diff --git a/Servers/WindowServer/WSWindow.cpp b/Servers/WindowServer/WSWindow.cpp
index bde22c0109..c63f3cce3b 100644
--- a/Servers/WindowServer/WSWindow.cpp
+++ b/Servers/WindowServer/WSWindow.cpp
@@ -91,7 +91,7 @@ void WSWindow::handle_mouse_event(const WSMouseEvent& event)
     m_client->post_message(server_message);
 }
 
-void WSWindow::on_message(WSMessage& message)
+void WSWindow::on_message(const WSMessage& message)
 {
     if (m_internal_owner)
         return m_internal_owner->on_message(message);
@@ -114,15 +114,15 @@ void WSWindow::on_message(WSMessage& message)
         break;
     case WSMessage::KeyDown:
         server_message.type = WSAPI_ServerMessage::Type::KeyDown;
-        server_message.key.character = static_cast<WSKeyEvent&>(message).character();
-        server_message.key.key = static_cast<WSKeyEvent&>(message).key();
-        server_message.key.modifiers = static_cast<WSKeyEvent&>(message).modifiers();
+        server_message.key.character = static_cast<const WSKeyEvent&>(message).character();
+        server_message.key.key = static_cast<const WSKeyEvent&>(message).key();
+        server_message.key.modifiers = static_cast<const WSKeyEvent&>(message).modifiers();
         break;
     case WSMessage::KeyUp:
         server_message.type = WSAPI_ServerMessage::Type::KeyUp;
-        server_message.key.character = static_cast<WSKeyEvent&>(message).character();
-        server_message.key.key = static_cast<WSKeyEvent&>(message).key();
-        server_message.key.modifiers = static_cast<WSKeyEvent&>(message).modifiers();
+        server_message.key.character = static_cast<const WSKeyEvent&>(message).character();
+        server_message.key.key = static_cast<const WSKeyEvent&>(message).key();
+        server_message.key.modifiers = static_cast<const WSKeyEvent&>(message).modifiers();
         break;
     case WSMessage::WindowActivated:
         server_message.type = WSAPI_ServerMessage::Type::WindowActivated;
@@ -135,8 +135,8 @@ void WSWindow::on_message(WSMessage& message)
         break;
     case WSMessage::WindowResized:
         server_message.type = WSAPI_ServerMessage::Type::WindowResized;
-        server_message.window.old_rect = static_cast<WSResizeEvent&>(message).old_rect();
-        server_message.window.rect = static_cast<WSResizeEvent&>(message).rect();
+        server_message.window.old_rect = static_cast<const WSResizeEvent&>(message).old_rect();
+        server_message.window.rect = static_cast<const WSResizeEvent&>(message).rect();
         break;
     default:
         break;
diff --git a/Servers/WindowServer/WSWindow.h b/Servers/WindowServer/WSWindow.h
index 624b951d57..c080951c15 100644
--- a/Servers/WindowServer/WSWindow.h
+++ b/Servers/WindowServer/WSWindow.h
@@ -64,7 +64,7 @@ public:
 
     void invalidate();
 
-    virtual void on_message(WSMessage&) override;
+    virtual void on_message(const WSMessage&) override;
 
     GraphicsBitmap* backing_store() { return m_backing_store.ptr(); }
     void set_backing_store(RetainPtr<GraphicsBitmap>&& backing_store)
diff --git a/Servers/WindowServer/WSWindowManager.cpp b/Servers/WindowServer/WSWindowManager.cpp
index 3791f66699..43d828eb3e 100644
--- a/Servers/WindowServer/WSWindowManager.cpp
+++ b/Servers/WindowServer/WSWindowManager.cpp
@@ -402,7 +402,7 @@ static CharacterBitmap* s_close_button_bitmap;
 static const int s_close_button_bitmap_width = 8;
 static const int s_close_button_bitmap_height = 9;
 
-void WSWindowManager::paint_window_frame(WSWindow& window)
+void WSWindowManager::paint_window_frame(const WSWindow& window)
 {
     //printf("[WM] paint_window_frame {%p}, rect: %d,%d %dx%d\n", &window, window.rect().x(), window.rect().y(), window.rect().width(), window.rect().height());
 
@@ -546,7 +546,7 @@ void WSWindowManager::notify_rect_changed(WSWindow& window, const Rect& old_rect
         m_switcher.refresh();
 }
 
-void WSWindowManager::handle_menu_mouse_event(WSMenu& menu, WSMouseEvent& event)
+void WSWindowManager::handle_menu_mouse_event(WSMenu& menu, const WSMouseEvent& event)
 {
     bool is_hover_with_any_menu_open = event.type() == WSMouseEvent::MouseMove && m_current_menu;
     bool is_mousedown_with_left_button = event.type() == WSMouseEvent::MouseDown && event.button() == MouseButton::Left;
@@ -577,7 +577,7 @@ void WSWindowManager::close_current_menu()
     m_current_menu = nullptr;
 }
 
-void WSWindowManager::handle_menubar_mouse_event(WSMouseEvent& event)
+void WSWindowManager::handle_menubar_mouse_event(const WSMouseEvent& event)
 {
     for_each_active_menubar_menu([&] (WSMenu& menu) {
         if (menu.rect_in_menubar().contains(event.position())) {
@@ -588,7 +588,7 @@ void WSWindowManager::handle_menubar_mouse_event(WSMouseEvent& event)
     });
 }
 
-void WSWindowManager::handle_close_button_mouse_event(WSWindow& window, WSMouseEvent& event)
+void WSWindowManager::handle_close_button_mouse_event(WSWindow& window, const WSMouseEvent& event)
 {
     if (event.type() == WSMessage::MouseDown && event.button() == MouseButton::Left) {
         WSMessage message(WSMessage::WindowCloseRequest);
@@ -597,7 +597,7 @@ void WSWindowManager::handle_close_button_mouse_event(WSWindow& window, WSMouseE
     }
 }
 
-void WSWindowManager::start_window_drag(WSWindow& window, WSMouseEvent& event)
+void WSWindowManager::start_window_drag(WSWindow& window, const WSMouseEvent& event)
 {
 #ifdef DRAG_DEBUG
     printf("[WM] Begin dragging WSWindow{%p}\n", &window);
@@ -609,7 +609,7 @@ void WSWindowManager::start_window_drag(WSWindow& window, WSMouseEvent& event)
     invalidate(window);
 }
 
-void WSWindowManager::start_window_resize(WSWindow& window, WSMouseEvent& event)
+void WSWindowManager::start_window_resize(WSWindow& window, const WSMouseEvent& event)
 {
     move_to_front_and_make_active(window);
     constexpr ResizeDirection direction_for_hot_area[3][3] = {
@@ -640,7 +640,7 @@ void WSWindowManager::start_window_resize(WSWindow& window, WSMouseEvent& event)
     invalidate(window);
 }
 
-bool WSWindowManager::process_ongoing_window_drag(WSMouseEvent& event, WSWindow*&)
+bool WSWindowManager::process_ongoing_window_drag(const WSMouseEvent& event, WSWindow*&)
 {
     if (!m_drag_window)
         return false;
@@ -667,7 +667,7 @@ bool WSWindowManager::process_ongoing_window_drag(WSMouseEvent& event, WSWindow*
     return false;
 }
 
-bool WSWindowManager::process_ongoing_window_resize(WSMouseEvent& event, WSWindow*&)
+bool WSWindowManager::process_ongoing_window_resize(const WSMouseEvent& event, WSWindow*&)
 {
     if (!m_resize_window)
         return false;
@@ -768,7 +768,7 @@ bool WSWindowManager::process_ongoing_window_resize(WSMouseEvent& event, WSWindo
     return true;
 }
 
-void WSWindowManager::process_mouse_event(WSMouseEvent& event, WSWindow*& event_window)
+void WSWindowManager::process_mouse_event(const WSMouseEvent& event, WSWindow*& event_window)
 {
     event_window = nullptr;
 
@@ -1051,17 +1051,17 @@ void WSWindowManager::draw_cursor()
     m_last_cursor_rect = cursor_rect;
 }
 
-void WSWindowManager::on_message(WSMessage& message)
+void WSWindowManager::on_message(const WSMessage& message)
 {
     if (message.is_mouse_event()) {
         WSWindow* event_window = nullptr;
-        process_mouse_event(static_cast<WSMouseEvent&>(message), event_window);
+        process_mouse_event(static_cast<const WSMouseEvent&>(message), event_window);
         set_hovered_window(event_window);
         return;
     }
 
     if (message.is_key_event()) {
-        auto& key_event = static_cast<WSKeyEvent&>(message);
+        auto& key_event = static_cast<const WSKeyEvent&>(message);
         m_keyboard_modifiers = key_event.modifiers();
 
         if (key_event.type() == WSMessage::KeyDown && key_event.modifiers() == Mod_Logo && key_event.key() == Key_Tab)
diff --git a/Servers/WindowServer/WSWindowManager.h b/Servers/WindowServer/WSWindowManager.h
index 84bcb990e6..40bae77754 100644
--- a/Servers/WindowServer/WSWindowManager.h
+++ b/Servers/WindowServer/WSWindowManager.h
@@ -88,15 +88,15 @@ public:
     Rect current_cursor_rect() const;
 
 private:
-    void process_mouse_event(WSMouseEvent&, WSWindow*& event_window);
-    bool process_ongoing_window_resize(WSMouseEvent&, WSWindow*& event_window);
-    bool process_ongoing_window_drag(WSMouseEvent&, WSWindow*& event_window);
-    void handle_menu_mouse_event(WSMenu&, WSMouseEvent&);
-    void handle_menubar_mouse_event(WSMouseEvent&);
-    void handle_close_button_mouse_event(WSWindow&, WSMouseEvent&);
-    void start_window_resize(WSWindow&, WSMouseEvent&);
-    void start_window_drag(WSWindow&, WSMouseEvent&);
-    void handle_client_request(WSAPIClientRequest&);
+    void process_mouse_event(const WSMouseEvent&, WSWindow*& event_window);
+    bool process_ongoing_window_resize(const WSMouseEvent&, WSWindow*& event_window);
+    bool process_ongoing_window_drag(const WSMouseEvent&, WSWindow*& event_window);
+    void handle_menu_mouse_event(WSMenu&, const WSMouseEvent&);
+    void handle_menubar_mouse_event(const WSMouseEvent&);
+    void handle_close_button_mouse_event(WSWindow&, const WSMouseEvent&);
+    void start_window_resize(WSWindow&, const WSMouseEvent&);
+    void start_window_drag(WSWindow&, const WSMouseEvent&);
+    void handle_client_request(const WSAPIClientRequest&);
     void set_active_window(WSWindow*);
     void set_hovered_window(WSWindow*);
     template<typename Callback> IterationDecision for_each_visible_window_of_type_from_back_to_front(WSWindowType, Callback);
@@ -105,9 +105,9 @@ private:
     template<typename Callback> IterationDecision for_each_visible_window_from_back_to_front(Callback);
     template<typename Callback> void for_each_active_menubar_menu(Callback);
     void close_current_menu();
-    virtual void on_message(WSMessage&) override;
+    virtual void on_message(const WSMessage&) override;
     void compose();
-    void paint_window_frame(WSWindow&);
+    void paint_window_frame(const WSWindow&);
     void flip_buffers();
     void tick_clock();
 
diff --git a/Servers/WindowServer/WSWindowSwitcher.cpp b/Servers/WindowServer/WSWindowSwitcher.cpp
index 3e91f3d45c..fd0765815c 100644
--- a/Servers/WindowServer/WSWindowSwitcher.cpp
+++ b/Servers/WindowServer/WSWindowSwitcher.cpp
@@ -116,6 +116,6 @@ void WSWindowSwitcher::refresh()
     draw();
 }
 
-void WSWindowSwitcher::on_message(WSMessage&)
+void WSWindowSwitcher::on_message(const WSMessage&)
 {
 }
diff --git a/Servers/WindowServer/WSWindowSwitcher.h b/Servers/WindowServer/WSWindowSwitcher.h
index 418cb4481d..8ea6e4d3bb 100644
--- a/Servers/WindowServer/WSWindowSwitcher.h
+++ b/Servers/WindowServer/WSWindowSwitcher.h
@@ -33,7 +33,7 @@ public:
     WSWindow* switcher_window() { return m_switcher_window.ptr(); }
 
 private:
-    virtual void on_message(WSMessage&) override;
+    virtual void on_message(const WSMessage&) override;
 
     OwnPtr<WSWindow> m_switcher_window;
     Rect m_rect;