DisplaySettings: Remove `root_widget()` from DisplaySettings

This fixes a weird dependency graph in DisplaySettings. The widget itself
(which is described in `gml` now), no longer contains `root_widget()`.

The widget itself has been moved into a tabbed pane, to get it ready
to add some more features and bring it more up to date with the current
UI code.

3 files changed, 19 insertions, 20 deletions

diff --git a/Applications/DisplaySettings/DisplaySettings.cpp b/Applications/DisplaySettings/DisplaySettings.cpp
index c59a8a93f5..6b49214269 100644
--- a/Applications/DisplaySettings/DisplaySettings.cpp
+++ b/Applications/DisplaySettings/DisplaySettings.cpp
@@ -90,12 +90,11 @@ void DisplaySettingsWidget::create_wallpaper_list()
 
 void DisplaySettingsWidget::create_frame()
 {
-    m_root_widget = GUI::Widget::construct();
-    m_root_widget->load_from_gml(display_settings_window_gml);
+    load_from_gml(display_settings_window_gml);
 
-    m_monitor_widget = *m_root_widget->find_descendant_of_type_named<DisplaySettings::MonitorWidget>("monitor_widget");
+    m_monitor_widget = *find_descendant_of_type_named<DisplaySettings::MonitorWidget>("monitor_widget");
 
-    m_wallpaper_combo = *m_root_widget->find_descendant_of_type_named<GUI::ComboBox>("wallpaper_combo");
+    m_wallpaper_combo = *find_descendant_of_type_named<GUI::ComboBox>("wallpaper_combo");
     m_wallpaper_combo->set_only_allow_values_from_model(true);
     m_wallpaper_combo->set_model(*GUI::ItemListModel<AK::String>::create(m_wallpapers));
     m_wallpaper_combo->on_change = [this](auto& text, const GUI::ModelIndex& index) {
@@ -120,11 +119,11 @@ void DisplaySettingsWidget::create_frame()
         m_monitor_widget->update();
     };
 
-    auto& button = *m_root_widget->find_descendant_of_type_named<GUI::Button>("wallpaper_open_button");
+    auto& button = *find_descendant_of_type_named<GUI::Button>("wallpaper_open_button");
     button.set_icon(Gfx::Bitmap::load_from_file("/res/icons/16x16/open.png"));
     button.set_button_style(Gfx::ButtonStyle::CoolBar);
     button.on_click = [this](auto) {
-        Optional<String> open_path = GUI::FilePicker::get_open_filepath(root_widget()->window(), "Select wallpaper from file system.");
+        Optional<String> open_path = GUI::FilePicker::get_open_filepath(nullptr, "Select wallpaper from file system.");
 
         if (!open_path.has_value())
             return;
@@ -134,7 +133,7 @@ void DisplaySettingsWidget::create_frame()
         m_wallpaper_combo->set_only_allow_values_from_model(true);
     };
 
-    m_mode_combo = *m_root_widget->find_descendant_of_type_named<GUI::ComboBox>("mode_combo");
+    m_mode_combo = *find_descendant_of_type_named<GUI::ComboBox>("mode_combo");
     m_mode_combo->set_only_allow_values_from_model(true);
     m_mode_combo->set_model(*GUI::ItemListModel<AK::String>::create(m_modes));
     m_mode_combo->on_change = [this](auto&, const GUI::ModelIndex& index) {
@@ -142,7 +141,7 @@ void DisplaySettingsWidget::create_frame()
         m_monitor_widget->update();
     };
 
-    m_resolution_combo = *m_root_widget->find_descendant_of_type_named<GUI::ComboBox>("resolution_combo");
+    m_resolution_combo = *find_descendant_of_type_named<GUI::ComboBox>("resolution_combo");
     m_resolution_combo->set_only_allow_values_from_model(true);
     m_resolution_combo->set_model(*GUI::ItemListModel<Gfx::IntSize>::create(m_resolutions));
     m_resolution_combo->on_change = [this](auto&, const GUI::ModelIndex& index) {
@@ -150,7 +149,7 @@ void DisplaySettingsWidget::create_frame()
         m_monitor_widget->update();
     };
 
-    m_color_input = *m_root_widget->find_descendant_of_type_named<GUI::ColorInput>("color_input");
+    m_color_input = *find_descendant_of_type_named<GUI::ColorInput>("color_input");
     m_color_input->set_color_has_alpha_channel(false);
     m_color_input->set_color_picker_title("Select color for desktop");
     m_color_input->on_change = [this] {
@@ -158,18 +157,18 @@ void DisplaySettingsWidget::create_frame()
         m_monitor_widget->update();
     };
 
-    auto& ok_button = *m_root_widget->find_descendant_of_type_named<GUI::Button>("ok_button");
+    auto& ok_button = *find_descendant_of_type_named<GUI::Button>("ok_button");
     ok_button.on_click = [this](auto) {
         send_settings_to_window_server();
         GUI::Application::the()->quit();
     };
 
-    auto& cancel_button = *m_root_widget->find_descendant_of_type_named<GUI::Button>("cancel_button");
+    auto& cancel_button = *find_descendant_of_type_named<GUI::Button>("cancel_button");
     cancel_button.on_click = [](auto) {
         GUI::Application::the()->quit();
     };
 
-    auto& apply_button = *m_root_widget->find_descendant_of_type_named<GUI::Button>("apply_button");
+    auto& apply_button = *find_descendant_of_type_named<GUI::Button>("apply_button");
     apply_button.on_click = [this](auto) {
         send_settings_to_window_server();
     };
@@ -250,7 +249,7 @@ void DisplaySettingsWidget::send_settings_to_window_server()
 {
     auto result = GUI::WindowServerConnection::the().send_sync<Messages::WindowServer::SetResolution>(m_monitor_widget->desktop_resolution());
     if (!result->success()) {
-        GUI::MessageBox::show(root_widget()->window(), String::formatted("Reverting to resolution {}x{}", result->resolution().width(), result->resolution().height()),
+        GUI::MessageBox::show(nullptr, String::formatted("Reverting to resolution {}x{}", result->resolution().width(), result->resolution().height()),
             "Unable to set resolution", GUI::MessageBox::Type::Error);
     }
 
diff --git a/Applications/DisplaySettings/DisplaySettings.h b/Applications/DisplaySettings/DisplaySettings.h
index df3452e278..30fb26ebed 100644
--- a/Applications/DisplaySettings/DisplaySettings.h
+++ b/Applications/DisplaySettings/DisplaySettings.h
@@ -36,8 +36,6 @@ class DisplaySettingsWidget : public GUI::Widget {
 public:
     DisplaySettingsWidget();
 
-    GUI::Widget* root_widget() { return m_root_widget; }
-
 private:
     void create_frame();
     void create_wallpaper_list();
@@ -49,7 +47,6 @@ private:
     Vector<String> m_modes;
     Vector<Gfx::IntSize> m_resolutions;
 
-    RefPtr<GUI::Widget> m_root_widget;
     RefPtr<DisplaySettings::MonitorWidget> m_monitor_widget;
     RefPtr<GUI::ComboBox> m_wallpaper_combo;
     RefPtr<GUI::ComboBox> m_mode_combo;
diff --git a/Applications/DisplaySettings/main.cpp b/Applications/DisplaySettings/main.cpp
index edb7cae10e..17697cbdd6 100644
--- a/Applications/DisplaySettings/main.cpp
+++ b/Applications/DisplaySettings/main.cpp
@@ -32,6 +32,7 @@
 #include <LibGUI/Icon.h>
 #include <LibGUI/Menu.h>
 #include <LibGUI/MenuBar.h>
+#include <LibGUI/TabWidget.h>
 #include <LibGUI/Widget.h>
 #include <LibGUI/Window.h>
 #include <LibGfx/Bitmap.h>
@@ -53,15 +54,17 @@ int main(int argc, char** argv)
 
     auto app_icon = GUI::Icon::default_icon("app-display-settings");
 
-    // FIXME: Clean up this bizarre object graph
-    auto instance = DisplaySettingsWidget::construct();
+    // Let's create the tab pane that we'll hook our widgets up to :^)
+    auto tab_widget = GUI::TabWidget::construct();
+    tab_widget->add_tab<DisplaySettingsWidget>("Display Settings");
+    tab_widget->set_fill_with_background_color(true); // No black backgrounds!
 
     auto window = GUI::Window::construct();
     dbgln("main window: {}", window);
     window->set_title("Display settings");
-    window->resize(360, 390);
+    window->resize(360, 410);
     window->set_resizable(false);
-    window->set_main_widget(instance->root_widget());
+    window->set_main_widget(tab_widget.ptr());
     window->set_icon(app_icon.bitmap_for_size(16));
 
     auto menubar = GUI::MenuBar::construct();