WindowServer+LibGUI: Add "frameless" window flag

This allows you to create windows with no title bar or window frame.

Libraries/LibGUI/Window.cpp

@@ -100,6 +100,7 @@ void Window::show()
         m_minimizable,
         m_resizable,
         m_fullscreen,
+        m_frameless,
         m_opacity_when_windowless,
         m_base_size,
         m_size_increment,

Libraries/LibGUI/Window.h

@@ -62,6 +62,9 @@ public:
     bool is_fullscreen() const { return m_fullscreen; }
     void set_fullscreen(bool);
 
+    bool is_frameless() const { return m_frameless; }
+    void set_frameless(bool frameless) { m_frameless = frameless; }
+
     bool is_resizable() const { return m_resizable; }
     void set_resizable(bool resizable) { m_resizable = resizable; }
 
@@ -219,6 +222,7 @@ private:
     bool m_resizable { true };
     bool m_minimizable { true };
     bool m_fullscreen { false };
+    bool m_frameless { false };
     bool m_layout_pending { false };
     bool m_visible_for_timer_purposes { true };
     bool m_visible { false };

Servers/WindowServer/ClientConnection.cpp

@@ -475,6 +475,8 @@ OwnPtr<Messages::WindowServer::CreateWindowResponse> ClientConnection::handle(co
         window->set_parent_window(*parent_window);
     }
 
+    window->set_frameless(message.frameless());
+
     window->set_has_alpha_channel(message.has_alpha_channel());
     window->set_title(message.title());
     if (!message.fullscreen()) {

Servers/WindowServer/Window.h

@@ -229,6 +229,9 @@ public:
     Vector<WeakPtr<Window>>& child_windows() { return m_child_windows; }
     const Vector<WeakPtr<Window>>& child_windows() const { return m_child_windows; }
 
+    void set_frameless(bool frameless) { m_frameless = frameless; }
+    bool is_frameless() const { return m_frameless; }
+
 private:
     void handle_mouse_event(const MouseEvent&);
     void update_menu_item_text(PopupMenuItem item);
@@ -259,6 +262,7 @@ private:
     WindowTileType m_tiled { WindowTileType::None };
     Gfx::Rect m_untiled_rect;
     bool m_occluded { false };
+    bool m_frameless { false };
     RefPtr<Gfx::Bitmap> m_backing_store;
     RefPtr<Gfx::Bitmap> m_last_backing_store;
     int m_window_id { -1 };

Servers/WindowServer/WindowFrame.cpp

@@ -257,6 +257,9 @@ void WindowFrame::paint_normal_frame(Gfx::Painter& painter)
 
 void WindowFrame::paint(Gfx::Painter& painter)
 {
+    if (m_window.is_frameless())
+        return;
+
     Gfx::PainterStateSaver saver(painter);
     painter.translate(rect().location());
 
@@ -274,6 +277,9 @@ void WindowFrame::paint(Gfx::Painter& painter)
 
 static Gfx::Rect frame_rect_for_window(Window& window, const Gfx::Rect& rect)
 {
+    if (window.is_frameless())
+        return rect;
+
     auto type = window.type();
 
     switch (type) {

Servers/WindowServer/WindowServer.ipc

@@ -36,6 +36,7 @@ endpoint WindowServer = 2
         bool minimizable,
         bool resizable,
         bool fullscreen,
+        bool frameless,
         float opacity,
         Gfx::Size base_size,
         Gfx::Size size_increment,