LibGUI+WindowServer: Provide default placement to windows

This prevents windows from being opened directly on top of eachother,
and provides default behavior for when window position is not specified.

The new behavior is as follows:
- Windows that have been created without a set position are assigned one
  by WindowServer.
- The assigned position is either offset from the last window that is
  still in an assigned position, or a default position if no such window
  is available.

Libraries/LibGUI/Window.cpp

@@ -62,7 +62,7 @@ Window::Window(Core::Object* parent)
     : Core::Object(parent)
 {
     all_windows->set(this);
-    m_rect_when_windowless = { 100, 400, 140, 140 };
+    m_rect_when_windowless = { -5000, -5000, 140, 140 };
     m_title_when_windowless = "GUI::Window";
 }
 
@@ -95,6 +95,7 @@ void Window::show()
     m_override_cursor = StandardCursor::None;
     auto response = WindowServerConnection::the().send_sync<Messages::WindowServer::CreateWindow>(
         m_rect_when_windowless,
+        !m_moved_by_client,
         m_has_alpha_channel,
         m_modal,
         m_minimizable,
@@ -192,6 +193,10 @@ Gfx::IntRect Window::rect() const
 
 void Window::set_rect(const Gfx::IntRect& a_rect)
 {
+    if (a_rect.location() != m_rect_when_windowless.location()) {
+        m_moved_by_client = true;
+    }
+
     m_rect_when_windowless = a_rect;
     if (!is_visible()) {
         if (m_main_widget)

Libraries/LibGUI/Window.h

@@ -262,6 +262,7 @@ private:
     bool m_visible_for_timer_purposes { true };
     bool m_visible { false };
     bool m_accessory { false };
+    bool m_moved_by_client { false };
 };
 
 }

Services/WindowServer/ClientConnection.cpp

@@ -407,6 +407,10 @@ OwnPtr<Messages::WindowServer::SetWindowRectResponse> ClientConnection::handle(c
         dbg() << "ClientConnection: Ignoring SetWindowRect request for fullscreen window";
         return nullptr;
     }
+
+    if (message.rect().location() != window.rect().location()) {
+        window.set_default_positioned(false);
+    }
     auto normalized_rect = normalize_window_rect(message.rect(), window.type());
     window.set_rect(normalized_rect);
     window.request_update(normalized_rect);
@@ -460,7 +464,12 @@ OwnPtr<Messages::WindowServer::CreateWindowResponse> ClientConnection::handle(co
     window->set_has_alpha_channel(message.has_alpha_channel());
     window->set_title(message.title());
     if (!message.fullscreen()) {
-        auto normalized_rect = normalize_window_rect(message.rect(), window->type());
+        auto rect = message.rect();
+        if (message.auto_position() && window->type() == WindowType::Normal) {
+            rect = { WindowManager::the().get_recommended_window_position({ 100, 100 }), message.rect().size() };
+            window->set_default_positioned(true);
+        }
+        auto normalized_rect = normalize_window_rect(rect, window->type());
         window->set_rect(normalized_rect);
     }
     if (window->type() == WindowType::Desktop) {

Services/WindowServer/Window.cpp

@@ -273,6 +273,7 @@ void Window::set_maximized(bool maximized)
     }
     m_frame.did_set_maximized({}, maximized);
     Core::EventLoop::current().post_event(*this, make<ResizeEvent>(old_rect, m_rect));
+    set_default_positioned(false);
 }
 
 void Window::set_resizable(bool resizable)
@@ -398,7 +399,7 @@ Window* Window::is_blocked_by_modal_window()
         if (window && !window->is_destroyed()) {
             if (window->is_modal())
                 return window;
-            
+
             if (auto* blocking_modal_window = window->is_blocked_by_modal_window())
                 return blocking_modal_window;
         }
@@ -601,7 +602,7 @@ bool Window::is_accessory() const
         return false;
     if (parent_window() != nullptr)
         return true;
-    
+
     // If accessory window was unparented, convert to a regular window
     const_cast<Window*>(this)->set_accessory(false);
     return false;

Services/WindowServer/Window.h

@@ -259,6 +259,9 @@ public:
     bool is_destroyed() const { return m_destroyed; }
     void destroy();
 
+    bool default_positioned() const { return m_default_positioned; }
+    void set_default_positioned(bool p) { m_default_positioned = p; }
+
 private:
     void handle_mouse_event(const MouseEvent&);
     void update_menu_item_text(PopupMenuItem item);
@@ -293,6 +296,7 @@ private:
     bool m_fullscreen { false };
     bool m_accessory { false };
     bool m_destroyed { false };
+    bool m_default_positioned { false };
     WindowTileType m_tiled { WindowTileType::None };
     Gfx::IntRect m_untiled_rect;
     bool m_occluded { false };

Services/WindowServer/WindowManager.cpp

@@ -442,6 +442,7 @@ void WindowManager::start_window_move(Window& window, const MouseEvent& event)
 #endif
     move_to_front_and_make_active(window);
     m_move_window = window.make_weak_ptr();
+    m_move_window->set_default_positioned(false);
     m_move_origin = event.position();
     m_move_window_origin = window.position();
     window.invalidate();
@@ -479,6 +480,10 @@ void WindowManager::start_window_resize(Window& window, const Gfx::IntPoint& pos
     m_resize_window_original_rect = window.rect();
 
     window.invalidate();
+
+    if (hot_area_row == 0 || hot_area_column == 0) {
+        m_resize_window->set_default_positioned(false);
+    }
 }
 
 void WindowManager::start_window_resize(Window& window, const MouseEvent& event)
@@ -1428,4 +1433,34 @@ void WindowManager::maximize_windows(Window& window, bool maximized)
     });
 }
 
+Gfx::IntPoint WindowManager::get_recommended_window_position(const Gfx::IntPoint& desired)
+{
+    // FIXME: Find a  better source for the width and height to shift by.
+    Gfx::IntPoint shift(8, palette().window_title_height() + 10);
+
+    // FIXME: Find a better source for this.
+    int taskbar_height = 28;
+    int menubar_height = MenuManager::the().menubar_rect().height();
+
+    const Window* overlap_window = nullptr;
+    for_each_visible_window_of_type_from_front_to_back(WindowType::Normal, [&](Window& window) {
+        if (window.default_positioned() && (!overlap_window || overlap_window->window_id() < window.window_id())) {
+            overlap_window = &window;
+        }
+        return IterationDecision::Continue;
+    });
+
+    Gfx::IntPoint point;
+    if (overlap_window) {
+        point = overlap_window->position() + shift;
+        point = { point.x() % Screen::the().width(),
+            (point.y() >= (Screen::the().height() - taskbar_height))
+                ? menubar_height + palette().window_title_height()
+                : point.y() };
+    } else {
+        point = desired;
+    }
+
+    return point;
+}
 }

Services/WindowServer/WindowManager.h

@@ -212,6 +212,8 @@ public:
         }
     }
 
+    Gfx::IntPoint get_recommended_window_position(const Gfx::IntPoint& desired);
+
 private:
     NonnullRefPtr<Cursor> get_cursor(const String& name);
     NonnullRefPtr<Cursor> get_cursor(const String& name, const Gfx::IntPoint& hotspot);

Services/WindowServer/WindowServer.ipc

@@ -32,6 +32,7 @@ endpoint WindowServer = 2
 
     CreateWindow(
         Gfx::IntRect rect,
+        bool auto_position,
         bool has_alpha_channel,
         bool modal,
         bool minimizable,