LibGUI+WindowServer: Don't use a WM IPC to initiate own window resize

The WM_* IPC messages are intended for "outsider" window management,
not for a client's own windows. Make a separate StartWindowResize
message for this.

This was the only reason that every IPC client had to know its server
side client ID.

Userland/Libraries/LibGUI/ResizeCorner.cpp

@@ -106,7 +106,7 @@ void ResizeCorner::paint_event(PaintEvent& event)
 void ResizeCorner::mousedown_event(MouseEvent& event)
 {
     if (event.button() == MouseButton::Left)
-        window()->start_wm_resize();
+        window()->start_interactive_resize();
     Widget::mousedown_event(event);
 }
 

Userland/Libraries/LibGUI/Window.cpp

@@ -774,9 +774,9 @@ void Window::apply_icon()
     WindowServerConnection::the().send_sync<Messages::WindowServer::SetWindowIconBitmap>(m_window_id, m_icon->to_shareable_bitmap());
 }
 
-void Window::start_wm_resize()
+void Window::start_interactive_resize()
 {
-    WindowServerConnection::the().post_message(Messages::WindowServer::WM_StartWindowResize(WindowServerConnection::the().my_client_id(), m_window_id));
+    WindowServerConnection::the().post_message(Messages::WindowServer::StartWindowResize(m_window_id));
 }
 
 Vector<Widget*> Window::focusable_widgets(FocusSource source) const

Userland/Libraries/LibGUI/Window.h

@@ -126,7 +126,7 @@ public:
     virtual void close();
     void move_to_front();
 
-    void start_wm_resize();
+    void start_interactive_resize();
 
     Widget* main_widget() { return m_main_widget; }
     const Widget* main_widget() const { return m_main_widget; }

Userland/Services/WindowServer/ClientConnection.cpp

@@ -673,6 +673,19 @@ void ClientConnection::handle(const Messages::WindowServer::WM_PopupWindowMenu&
     }
 }
 
+void ClientConnection::handle(const Messages::WindowServer::StartWindowResize& request)
+{
+    auto it = m_windows.find(request.window_id());
+    if (it == m_windows.end()) {
+        did_misbehave("WM_StartWindowResize: Bad window ID");
+        return;
+    }
+    auto& window = *(*it).value;
+    // FIXME: We are cheating a bit here by using the current cursor location and hard-coding the left button.
+    //        Maybe the client should be allowed to specify what initiated this request?
+    WindowManager::the().start_window_resize(window, Screen::the().cursor_location(), MouseButton::Left);
+}
+
 void ClientConnection::handle(const Messages::WindowServer::WM_StartWindowResize& request)
 {
     auto* client = ClientConnection::from_client_id(request.client_id());

Userland/Services/WindowServer/ClientConnection.h

@@ -105,6 +105,7 @@ private:
     virtual OwnPtr<Messages::WindowServer::SetWindowTitleResponse> handle(const Messages::WindowServer::SetWindowTitle&) override;
     virtual OwnPtr<Messages::WindowServer::GetWindowTitleResponse> handle(const Messages::WindowServer::GetWindowTitle&) override;
     virtual OwnPtr<Messages::WindowServer::IsMaximizedResponse> handle(const Messages::WindowServer::IsMaximized&) override;
+    virtual void handle(const Messages::WindowServer::StartWindowResize&) override;
     virtual OwnPtr<Messages::WindowServer::SetWindowRectResponse> handle(const Messages::WindowServer::SetWindowRect&) override;
     virtual OwnPtr<Messages::WindowServer::GetWindowRectResponse> handle(const Messages::WindowServer::GetWindowRect&) override;
     virtual OwnPtr<Messages::WindowServer::GetWindowRectInMenubarResponse> handle(const Messages::WindowServer::GetWindowRectInMenubar&) override;

Userland/Services/WindowServer/WindowServer.ipc

@@ -60,6 +60,8 @@ endpoint WindowServer = 2
 
     GetWindowRectInMenubar(i32 window_id) => (Gfx::IntRect rect)
 
+    StartWindowResize(i32 window_id) =|
+
     IsMaximized(i32 window_id) => (bool maximized)
 
     InvalidateRect(i32 window_id, Vector<Gfx::IntRect> rects, bool ignore_occlusion) =|