Applications+Demos+LibGUI: Migrate to fallible WizardDialogs and Pages

And port page text to String. Also removes WizardDialog::show() helper
as all current implementations prefer to derive their own Dialog.

Userland/Applications/FontEditor/MainWidget.cpp

@@ -116,10 +116,13 @@ ErrorOr<void> MainWidget::create_actions()
     m_new_action = GUI::Action::create("&New Font...", { Mod_Ctrl, Key_N }, g_resources.new_font, [this](auto&) {
         if (!request_close())
             return;
-        auto new_font_wizard = NewFontDialog::construct(window());
+        auto maybe_wizard = NewFontDialog::create(window());
-        if (new_font_wizard->exec() != GUI::Dialog::ExecResult::OK)
+        if (maybe_wizard.is_error())
+            return show_error(maybe_wizard.release_error(), "Creating font wizard failed"sv);
+        auto wizard = maybe_wizard.release_value();
+        if (wizard->exec() != GUI::Dialog::ExecResult::OK)
             return;
-        auto maybe_font = new_font_wizard->create_font();
+        auto maybe_font = wizard->create_font();
         if (maybe_font.is_error())
             return show_error(maybe_font.release_error(), "Creating new font failed"sv);
         if (auto result = initialize({}, move(maybe_font.value())); result.is_error())

Userland/Applications/FontEditor/NewFontDialog.cpp

@@ -122,13 +122,19 @@ private:
 
 REGISTER_WIDGET(FontEditor, GlyphPreviewWidget);
 
-NewFontDialog::NewFontDialog(GUI::Window* parent_window)
+ErrorOr<NonnullRefPtr<NewFontDialog>> NewFontDialog::create(GUI::Window* parent_window)
-    : GUI::WizardDialog(parent_window)
 {
-    set_title("New Font");
+    auto dialog = TRY(adopt_nonnull_ref_or_enomem(new (nothrow) NewFontDialog(parent_window)));
+    TRY(dialog->build());
+    return dialog;
+}
 
-    m_font_properties_page = GUI::WizardPage::construct("Typeface properties", "Edit details about this font.");
+ErrorOr<void> NewFontDialog::build()
-    m_font_properties_page->body_widget().load_from_gml(new_font_dialog_page_1_gml).release_value_but_fixme_should_propagate_errors();
+{
+    TRY(GUI::WizardDialog::build());
+
+    m_font_properties_page = TRY(GUI::WizardPage::create("Typeface properties"sv, "Edit details about this font."sv));
+    TRY(m_font_properties_page->body_widget().load_from_gml(new_font_dialog_page_1_gml));
 
     m_name_textbox = m_font_properties_page->body_widget().find_descendant_of_type_named<GUI::TextBox>("name_textbox");
     m_family_textbox = m_font_properties_page->body_widget().find_descendant_of_type_named<GUI::TextBox>("family_textbox");
@@ -136,14 +142,16 @@ NewFontDialog::NewFontDialog(GUI::Window* parent_window)
     m_slope_combobox = m_font_properties_page->body_widget().find_descendant_of_type_named<GUI::ComboBox>("slope_combobox");
     m_presentation_spinbox = m_font_properties_page->body_widget().find_descendant_of_type_named<GUI::SpinBox>("presentation_spinbox");
 
+    TRY(m_font_weight_list.try_ensure_capacity(Gfx::font_weight_names.size()));
     for (auto& it : Gfx::font_weight_names)
-        m_font_weight_list.append(it.name);
+        m_font_weight_list.unchecked_append(TRY(String::from_utf8(it.name)));
-    m_weight_combobox->set_model(*GUI::ItemListModel<DeprecatedString>::create(m_font_weight_list));
+    m_weight_combobox->set_model(TRY(GUI::ItemListModel<String>::try_create(m_font_weight_list)));
     m_weight_combobox->set_selected_index(3);
 
+    TRY(m_font_slope_list.try_ensure_capacity(Gfx::font_slope_names.size()));
     for (auto& it : Gfx::font_slope_names)
-        m_font_slope_list.append(it.name);
+        m_font_slope_list.unchecked_append(TRY(String::from_utf8(it.name)));
-    m_slope_combobox->set_model(*GUI::ItemListModel<DeprecatedString>::create(m_font_slope_list));
+    m_slope_combobox->set_model(TRY(GUI::ItemListModel<String>::try_create(m_font_slope_list)));
     m_slope_combobox->set_selected_index(0);
 
     m_presentation_spinbox->set_value(12);
@@ -155,8 +163,8 @@ NewFontDialog::NewFontDialog(GUI::Window* parent_window)
         return m_glyph_properties_page;
     };
 
-    m_glyph_properties_page = GUI::WizardPage::construct("Glyph properties", "Edit details about this font.");
+    m_glyph_properties_page = TRY(GUI::WizardPage::create("Glyph properties"sv, "Edit details about this font."sv));
-    m_glyph_properties_page->body_widget().load_from_gml(new_font_dialog_page_2_gml).release_value_but_fixme_should_propagate_errors();
+    TRY(m_glyph_properties_page->body_widget().load_from_gml(new_font_dialog_page_2_gml));
     m_glyph_properties_page->set_is_final_page(true);
 
     m_glyph_height_spinbox = m_glyph_properties_page->body_widget().find_descendant_of_type_named<GUI::SpinBox>("height_spinbox");
@@ -197,6 +205,15 @@ NewFontDialog::NewFontDialog(GUI::Window* parent_window)
     };
 
     push_page(*m_font_properties_page);
+
+    return {};
+}
+
+NewFontDialog::NewFontDialog(GUI::Window* parent_window)
+    : GUI::WizardDialog(parent_window)
+{
+    set_title("New Font");
+    set_icon(parent_window->icon());
 }
 
 void NewFontDialog::save_metadata()

Userland/Applications/FontEditor/NewFontDialog.h

@@ -12,13 +12,17 @@
 #include <LibGfx/Font/BitmapFont.h>
 
 class NewFontDialog final : public GUI::WizardDialog {
-    C_OBJECT(NewFontDialog);
+    C_OBJECT_ABSTRACT(NewFontDialog);
 
 public:
+    static ErrorOr<NonnullRefPtr<NewFontDialog>> create(GUI::Window* parent_window);
+
     ErrorOr<NonnullRefPtr<Gfx::BitmapFont>> create_font();
 
 private:
-    NewFontDialog(GUI::Window* parent_window);
+    explicit NewFontDialog(GUI::Window* parent_window);
+
+    virtual ErrorOr<void> build() override;
 
     void save_metadata();
 
@@ -51,6 +55,6 @@ private:
     RefPtr<GUI::SpinBox> m_spacing_spinbox;
     RefPtr<GUI::CheckBox> m_fixed_width_checkbox;
 
-    Vector<DeprecatedString> m_font_weight_list;
+    Vector<String> m_font_weight_list;
-    Vector<DeprecatedString> m_font_slope_list;
+    Vector<String> m_font_slope_list;
 };

Userland/Applications/Spreadsheet/ExportDialog.cpp

@@ -34,9 +34,10 @@ CSVExportDialogPage::CSVExportDialogPage(Sheet const& sheet)
 {
     m_headers.extend(m_data.take_first());
 
-    m_page = GUI::WizardPage::construct(
+    m_page = GUI::WizardPage::create(
-        "CSV Export Options",
+        "CSV Export Options"sv,
-        "Please select the options for the csv file you wish to export to");
+        "Please select the options for the csv file you wish to export to"sv)
+                 .release_value_but_fixme_should_propagate_errors();
 
     m_page->body_widget().load_from_gml(csv_export_gml).release_value_but_fixme_should_propagate_errors();
     m_page->set_is_final_page(true);
@@ -180,7 +181,7 @@ void CSVExportDialogPage::update_preview()
 
 ErrorOr<void> ExportDialog::make_and_run_for(StringView mime, Core::File& file, DeprecatedString filename, Workbook& workbook)
 {
-    auto wizard = GUI::WizardDialog::construct(GUI::Application::the()->active_window());
+    auto wizard = TRY(GUI::WizardDialog::create(GUI::Application::the()->active_window()));
     wizard->set_title("File Export Wizard");
     wizard->set_icon(GUI::Icon::default_icon("app-spreadsheet"sv).bitmap_for_size(16));
 
@@ -213,9 +214,9 @@ ErrorOr<void> ExportDialog::make_and_run_for(StringView mime, Core::File& file,
     } else if (mime == "application/x-sheets+json") {
         return export_worksheet();
     } else {
-        auto page = GUI::WizardPage::construct(
+        auto page = TRY(GUI::WizardPage::create(
-            "Export File Format",
+            "Export File Format"sv,
-            DeprecatedString::formatted("Select the format you wish to export to '{}' as", LexicalPath::basename(filename)));
+            TRY(String::formatted("Select the format you wish to export to '{}' as", LexicalPath::basename(filename)))));
 
         page->on_next_page = [] { return nullptr; };
 

Userland/Applications/Spreadsheet/ImportDialog.cpp

@@ -27,9 +27,10 @@ namespace Spreadsheet {
 CSVImportDialogPage::CSVImportDialogPage(StringView csv)
     : m_csv(csv)
 {
-    m_page = GUI::WizardPage::construct(
+    m_page = GUI::WizardPage::create(
-        "CSV Import Options",
+        "CSV Import Options"sv,
-        "Please select the options for the csv file you wish to import");
+        "Please select the options for the csv file you wish to import"sv)
+                 .release_value_but_fixme_should_propagate_errors();
 
     m_page->body_widget().load_from_gml(csv_import_gml).release_value_but_fixme_should_propagate_errors();
     m_page->set_is_final_page(true);
@@ -178,7 +179,7 @@ void CSVImportDialogPage::update_preview()
 
 ErrorOr<Vector<NonnullRefPtr<Sheet>>, DeprecatedString> ImportDialog::make_and_run_for(GUI::Window& parent, StringView mime, String const& filename, Core::File& file, Workbook& workbook)
 {
-    auto wizard = GUI::WizardDialog::construct(&parent);
+    auto wizard = GUI::WizardDialog::create(&parent).release_value_but_fixme_should_propagate_errors();
     wizard->set_title("File Import Wizard");
     wizard->set_icon(GUI::Icon::default_icon("app-spreadsheet"sv).bitmap_for_size(16));
 
@@ -244,9 +245,10 @@ ErrorOr<Vector<NonnullRefPtr<Sheet>>, DeprecatedString> ImportDialog::make_and_r
     } else if (mime == "application/x-sheets+json") {
         return import_worksheet();
     } else {
-        auto page = GUI::WizardPage::construct(
+        auto page = GUI::WizardPage::create(
-            "Import File Format",
+            "Import File Format"sv,
-            DeprecatedString::formatted("Select the format you wish to import '{}' as", LexicalPath::basename(filename.to_deprecated_string())));
+            DeprecatedString::formatted("Select the format you wish to import '{}' as", LexicalPath::basename(filename.to_deprecated_string())))
+                        .release_value_but_fixme_should_propagate_errors();
 
         page->on_next_page = [] { return nullptr; };
 

Userland/Demos/WidgetGallery/DemoWizardDialog.cpp

@@ -15,18 +15,22 @@
 DemoWizardDialog::DemoWizardDialog(GUI::Window* parent_window)
     : GUI::WizardDialog(parent_window)
 {
+    set_title("Demo Wizard");
+    build().release_value_but_fixme_should_propagate_errors();
+
     // Create the front cover
-    m_front_page = GUI::CoverWizardPage::try_create().release_value_but_fixme_should_propagate_errors();
+    m_front_page = GUI::CoverWizardPage::create(
-    m_front_page->set_header_text("Welcome to the SerenityOS demo wizard!");
+        "Welcome to the SerenityOS demo wizard!"sv,
-    m_front_page->set_body_text("This wizard demonstrates the amazing wizardry\ncapabilities of LibGUI :^)");
+        "This wizard demonstrates the amazing wizardry\ncapabilities of LibGUI :^)"sv)
+                       .release_value_but_fixme_should_propagate_errors();
     m_front_page->on_next_page = [&]() {
         return m_page_1;
     };
 
     // Create Page 1
-    m_page_1 = GUI::WizardPage::try_create(
+    m_page_1 = GUI::WizardPage::create(
-        "Installation location",
+        "Installation location"sv,
-        "Choose where Demo Application is installed on your computer.")
+        "Choose where Demo Application is installed on your computer."sv)
                    .release_value_but_fixme_should_propagate_errors();
     m_page_1->body_widget().load_from_gml(demo_wizard_page_1_gml).release_value_but_fixme_should_propagate_errors();
     m_page_1_location_text_box = m_page_1->body_widget().find_descendant_of_type_named<GUI::TextBox>("page_1_location_text_box");
@@ -35,9 +39,9 @@ DemoWizardDialog::DemoWizardDialog(GUI::Window* parent_window)
     };
 
     // Create Page 2 with a progress bar :^)
-    m_page_2 = GUI::WizardPage::try_create(
+    m_page_2 = GUI::WizardPage::create(
-        "Installation in progress...",
+        "Installation in progress..."sv,
-        "Please wait. Do not turn off your computer.")
+        "Please wait. Do not turn off your computer."sv)
                    .release_value_but_fixme_should_propagate_errors();
     m_page_2->body_widget().load_from_gml(demo_wizard_page_2_gml).release_value_but_fixme_should_propagate_errors();
     m_page_2_progressbar = m_page_2->body_widget().find_descendant_of_type_named<GUI::Progressbar>("page_2_progressbar");
@@ -66,9 +70,10 @@ DemoWizardDialog::DemoWizardDialog(GUI::Window* parent_window)
     // Don't set a on_next_page handler for page 2 as we automatically navigate to the final page on progress completion
 
     // Create the back cover
-    m_back_page = GUI::CoverWizardPage::try_create().release_value_but_fixme_should_propagate_errors();
+    m_back_page = GUI::CoverWizardPage::create(
-    m_back_page->set_header_text("Wizard complete.");
+        "Wizard complete."sv,
-    m_back_page->set_body_text("That concludes the SerenityOS demo wizard :^)");
+        "That concludes the SerenityOS demo wizard :^)"sv)
+                      .release_value_but_fixme_should_propagate_errors();
     m_back_page->set_is_final_page(true);
 
     push_page(*m_front_page);

Userland/Libraries/LibGUI/Wizards/CoverWizardPage.cpp

@@ -13,36 +13,44 @@
 
 namespace GUI {
 
-CoverWizardPage::CoverWizardPage()
+ErrorOr<NonnullRefPtr<CoverWizardPage>> CoverWizardPage::create(StringView title, StringView subtitle)
-    : AbstractWizardPage()
+{
+    auto page = TRY(adopt_nonnull_ref_or_enomem(new (nothrow) CoverWizardPage()));
+    TRY(page->build(TRY(String::from_utf8(title)), TRY(String::from_utf8(subtitle))));
+    return page;
+}
+
+ErrorOr<void> CoverWizardPage::build(String title, String subtitle)
 {
     set_fill_with_background_color(true);
     set_background_role(Gfx::ColorRole::Base);
-    set_layout<HorizontalBoxLayout>();
+    TRY(try_set_layout<HorizontalBoxLayout>());
-    m_banner_image_widget = add<ImageWidget>();
+    m_banner_image_widget = TRY(try_add<ImageWidget>());
     m_banner_image_widget->set_fixed_size(160, 315);
     m_banner_image_widget->load_from_file("/res/graphics/wizard-banner-simple.png"sv);
 
-    m_content_widget = add<Widget>();
+    m_content_widget = TRY(try_add<Widget>());
-    m_content_widget->set_layout<VerticalBoxLayout>(20);
+    TRY(m_content_widget->try_set_layout<VerticalBoxLayout>(20));
 
-    m_header_label = m_content_widget->add<Label>();
+    m_header_label = TRY(m_content_widget->try_add<Label>(move(title)));
     m_header_label->set_font(Gfx::FontDatabase::the().get("Pebbleton", 14, 700, Gfx::FontWidth::Normal, 0));
     m_header_label->set_text_alignment(Gfx::TextAlignment::TopLeft);
     m_header_label->set_fixed_height(48);
 
-    m_body_label = m_content_widget->add<Label>();
+    m_body_label = TRY(m_content_widget->try_add<Label>(move(subtitle)));
     m_body_label->set_text_alignment(Gfx::TextAlignment::TopLeft);
+
+    return {};
 }
 
-void CoverWizardPage::set_header_text(DeprecatedString const& text)
+void CoverWizardPage::set_header_text(String text)
 {
-    m_header_label->set_text(String::from_deprecated_string(text).release_value_but_fixme_should_propagate_errors());
+    m_header_label->set_text(move(text));
 }
 
-void CoverWizardPage::set_body_text(DeprecatedString const& text)
+void CoverWizardPage::set_body_text(String text)
 {
-    m_body_label->set_text(String::from_deprecated_string(text).release_value_but_fixme_should_propagate_errors());
+    m_body_label->set_text(move(text));
 }
 
 }

Userland/Libraries/LibGUI/Wizards/CoverWizardPage.h

@@ -14,15 +14,20 @@
 namespace GUI {
 
 class CoverWizardPage : public AbstractWizardPage {
-    C_OBJECT(CoverWizardPage);
+    C_OBJECT_ABSTRACT(CoverWizardPage);
+
+    static ErrorOr<NonnullRefPtr<CoverWizardPage>> create(StringView title, StringView subtitle);
 
     ImageWidget& banner_image_widget() { return *m_banner_image_widget; }
 
-    void set_header_text(DeprecatedString const& text);
+    void set_header_text(String);
-    void set_body_text(DeprecatedString const& text);
+    void set_body_text(String);
+
+protected:
+    virtual ErrorOr<void> build(String title, String subtitle);
 
 private:
-    explicit CoverWizardPage();
+    CoverWizardPage() = default;
 
     RefPtr<ImageWidget> m_banner_image_widget;
     RefPtr<Widget> m_content_widget;

Userland/Libraries/LibGUI/Wizards/WizardDialog.cpp

@@ -16,39 +16,37 @@
 
 namespace GUI {
 
-WizardDialog::WizardDialog(Window* parent_window)
+ErrorOr<NonnullRefPtr<WizardDialog>> WizardDialog::create(Window* parent_window)
-    : Dialog(parent_window)
-    , m_page_stack()
 {
-    resize(500, 360);
+    auto dialog = TRY(adopt_nonnull_ref_or_enomem(new (nothrow) WizardDialog(parent_window)));
-    set_title(DeprecatedString::formatted("Sample wizard"));
+    TRY(dialog->build());
-    set_resizable(false);
+    return dialog;
+}
 
-    if (parent_window)
+ErrorOr<void> WizardDialog::build()
-        set_icon(parent_window->icon());
+{
-
+    auto main_widget = TRY(set_main_widget<Widget>());
-    auto main_widget = set_main_widget<Widget>().release_value_but_fixme_should_propagate_errors();
     main_widget->set_fill_with_background_color(true);
-    main_widget->set_layout<VerticalBoxLayout>(GUI::Margins {}, 0);
+    TRY(main_widget->try_set_layout<VerticalBoxLayout>(Margins {}, 0));
 
-    m_page_container_widget = main_widget->add<Widget>();
+    m_page_container_widget = TRY(main_widget->try_add<Widget>());
     m_page_container_widget->set_fixed_size(500, 315);
-    m_page_container_widget->set_layout<VerticalBoxLayout>();
+    TRY(m_page_container_widget->try_set_layout<VerticalBoxLayout>());
 
-    auto& separator = main_widget->add<SeparatorWidget>(Gfx::Orientation::Horizontal);
+    auto separator = TRY(main_widget->try_add<SeparatorWidget>(Gfx::Orientation::Horizontal));
-    separator.set_fixed_height(2);
+    separator->set_fixed_height(2);
 
-    auto& nav_container_widget = main_widget->add<Widget>();
+    auto nav_container_widget = TRY(main_widget->try_add<Widget>());
-    nav_container_widget.set_layout<HorizontalBoxLayout>(GUI::Margins { 0, 10 }, 0);
+    TRY(nav_container_widget->try_set_layout<HorizontalBoxLayout>(Margins { 0, 10 }, 0));
-    nav_container_widget.set_fixed_height(42);
+    nav_container_widget->set_fixed_height(42);
-    nav_container_widget.add_spacer().release_value_but_fixme_should_propagate_errors();
+    TRY(nav_container_widget->add_spacer());
 
-    m_back_button = nav_container_widget.add<DialogButton>("< Back"_short_string);
+    m_back_button = TRY(nav_container_widget->try_add<DialogButton>("< Back"_short_string));
     m_back_button->on_click = [&](auto) {
         pop_page();
     };
 
-    m_next_button = nav_container_widget.add<DialogButton>("Next >"_short_string);
+    m_next_button = TRY(nav_container_widget->try_add<DialogButton>("Next >"_short_string));
     m_next_button->on_click = [&](auto) {
         VERIFY(has_pages());
 
@@ -62,15 +60,25 @@ WizardDialog::WizardDialog(Window* parent_window)
         push_page(*next_page);
     };
 
-    auto& button_spacer = nav_container_widget.add<Widget>();
+    auto button_spacer = TRY(nav_container_widget->try_add<Widget>());
-    button_spacer.set_fixed_width(10);
+    button_spacer->set_fixed_width(10);
 
-    m_cancel_button = nav_container_widget.add<DialogButton>("Cancel"_short_string);
+    m_cancel_button = TRY(nav_container_widget->try_add<DialogButton>("Cancel"_short_string));
     m_cancel_button->on_click = [&](auto) {
         handle_cancel();
     };
 
     update_navigation();
+
+    return {};
+}
+
+WizardDialog::WizardDialog(Window* parent_window)
+    : Dialog(parent_window)
+    , m_page_stack()
+{
+    resize(500, 360);
+    set_resizable(false);
 }
 
 void WizardDialog::push_page(AbstractWizardPage& page)

Userland/Libraries/LibGUI/Wizards/WizardDialog.h

@@ -13,16 +13,11 @@
 namespace GUI {
 
 class WizardDialog : public Dialog {
-    C_OBJECT(WizardDialog)
+    C_OBJECT_ABSTRACT(WizardDialog)
 public:
     virtual ~WizardDialog() override = default;
 
-    static void show(AbstractWizardPage& first_page, Window* parent_window = nullptr)
+    static ErrorOr<NonnullRefPtr<WizardDialog>> create(Window* parent_window);
-    {
-        auto dialog = WizardDialog::construct(parent_window);
-        dialog->push_page(first_page);
-        dialog->exec();
-    }
 
     Function<void()> on_cancel;
 
@@ -36,8 +31,9 @@ public:
     inline bool has_pages() const { return !m_page_stack.is_empty(); }
 
 protected:
-    WizardDialog(Window* parent_window);
+    explicit WizardDialog(Window* parent_window);
 
+    virtual ErrorOr<void> build();
     virtual void handle_cancel();
 
 private:

Userland/Libraries/LibGUI/Wizards/WizardPage.cpp

@@ -14,41 +14,50 @@
 
 namespace GUI {
 
-WizardPage::WizardPage(DeprecatedString const& title_text, DeprecatedString const& subtitle_text)
+ErrorOr<NonnullRefPtr<WizardPage>> WizardPage::create(StringView title, StringView subtitle)
-    : AbstractWizardPage()
 {
-    set_layout<VerticalBoxLayout>(GUI::Margins {}, 0);
+    auto page = TRY(adopt_nonnull_ref_or_enomem(new (nothrow) WizardPage()));
+    TRY(page->build(TRY(String::from_utf8(title)), TRY(String::from_utf8(subtitle))));
+    return page;
+}
 
-    auto& header_widget = add<Widget>();
+ErrorOr<void> WizardPage::build(String title, String subtitle)
-    header_widget.set_fill_with_background_color(true);
+{
-    header_widget.set_background_role(Gfx::ColorRole::Base);
+    TRY(try_set_layout<VerticalBoxLayout>(Margins {}, 0));
-    header_widget.set_fixed_height(58);
 
-    header_widget.set_layout<VerticalBoxLayout>(GUI::Margins { 15, 30, 0 });
+    auto header_widget = TRY(try_add<Widget>());
-    m_title_label = header_widget.add<Label>(String::from_deprecated_string(title_text).release_value_but_fixme_should_propagate_errors());
+    header_widget->set_fill_with_background_color(true);
+    header_widget->set_background_role(Gfx::ColorRole::Base);
+    header_widget->set_fixed_height(58);
+
+    TRY(header_widget->try_set_layout<VerticalBoxLayout>(Margins { 15, 30, 0 }));
+    m_title_label = TRY(header_widget->try_add<Label>(move(title)));
     m_title_label->set_font(Gfx::FontDatabase::default_font().bold_variant());
     m_title_label->set_fixed_height(m_title_label->font().pixel_size_rounded_up() + 2);
     m_title_label->set_text_alignment(Gfx::TextAlignment::TopLeft);
-    m_subtitle_label = header_widget.add<Label>(String::from_deprecated_string(subtitle_text).release_value_but_fixme_should_propagate_errors());
+
+    m_subtitle_label = TRY(header_widget->try_add<Label>(move(subtitle)));
     m_subtitle_label->set_text_alignment(Gfx::TextAlignment::TopLeft);
     m_subtitle_label->set_fixed_height(m_subtitle_label->font().pixel_size_rounded_up());
-    header_widget.add_spacer().release_value_but_fixme_should_propagate_errors();
+    TRY(header_widget->add_spacer());
 
-    auto& separator = add<SeparatorWidget>(Gfx::Orientation::Horizontal);
+    auto separator = TRY(try_add<SeparatorWidget>(Gfx::Orientation::Horizontal));
-    separator.set_fixed_height(2);
+    separator->set_fixed_height(2);
 
-    m_body_widget = add<Widget>();
+    m_body_widget = TRY(try_add<Widget>());
-    m_body_widget->set_layout<VerticalBoxLayout>(20);
+    TRY(m_body_widget->try_set_layout<VerticalBoxLayout>(20));
+
+    return {};
 }
 
-void WizardPage::set_page_title(DeprecatedString const& text)
+void WizardPage::set_page_title(String text)
 {
-    m_title_label->set_text(String::from_deprecated_string(text).release_value_but_fixme_should_propagate_errors());
+    m_title_label->set_text(move(text));
 }
 
-void WizardPage::set_page_subtitle(DeprecatedString const& text)
+void WizardPage::set_page_subtitle(String text)
 {
-    m_subtitle_label->set_text(String::from_deprecated_string(text).release_value_but_fixme_should_propagate_errors());
+    m_subtitle_label->set_text(move(text));
 }
 
 }

Userland/Libraries/LibGUI/Wizards/WizardPage.h

@@ -14,15 +14,20 @@
 namespace GUI {
 
 class WizardPage : public AbstractWizardPage {
-    C_OBJECT(WizardPage);
+    C_OBJECT_ABSTRACT(WizardPage);
+
+    static ErrorOr<NonnullRefPtr<WizardPage>> create(StringView title, StringView subtitle);
 
     Widget& body_widget() { return *m_body_widget; };
 
-    void set_page_title(DeprecatedString const& text);
+    void set_page_title(String);
-    void set_page_subtitle(DeprecatedString const& text);
+    void set_page_subtitle(String);
+
+protected:
+    virtual ErrorOr<void> build(String title, String subtitle);
 
 private:
-    explicit WizardPage(DeprecatedString const& title_text, DeprecatedString const& subtitle_text);
+    WizardPage() = default;
 
     RefPtr<Widget> m_body_widget;