HexEditor: Add Help->Manual entry in Menu

Userland/Applications/HexEditor/CMakeLists.txt

@@ -21,4 +21,4 @@ set(SOURCES
 )
 
 serenity_app(HexEditor ICON app-hex-editor)
-target_link_libraries(HexEditor LibGUI LibConfig LibFileSystemAccessClient LibMain)
+target_link_libraries(HexEditor LibGUI LibConfig LibDesktop LibFileSystemAccessClient LibMain)

Userland/Applications/HexEditor/HexEditorWidget.cpp

@@ -18,6 +18,7 @@
 #include <Applications/HexEditor/HexEditorWindowGML.h>
 #include <LibConfig/Client.h>
 #include <LibCore/File.h>
+#include <LibDesktop/Launcher.h>
 #include <LibFileSystemAccessClient/Client.h>
 #include <LibGUI/Action.h>
 #include <LibGUI/BoxLayout.h>
@@ -468,6 +469,9 @@ void HexEditorWidget::initialize_menubar(GUI::Window& window)
     little_endian_mode->set_checked(true);
 
     auto& help_menu = window.add_menu("&Help");
+    help_menu.add_action(GUI::CommonActions::make_help_action([](auto&) {
+        Desktop::Launcher::open(URL::create_with_file_protocol("/usr/share/man/man1/HexEditor.md"), "/bin/Help");
+    }));
     help_menu.add_action(GUI::CommonActions::make_about_action("Hex Editor", GUI::Icon::default_icon("app-hex-editor"sv), &window));
 }
 

Userland/Applications/HexEditor/main.cpp

@@ -9,6 +9,7 @@
 #include "HexEditorWidget.h"
 #include <LibConfig/Client.h>
 #include <LibCore/System.h>
+#include <LibDesktop/Launcher.h>
 #include <LibFileSystemAccessClient/Client.h>
 #include <LibGUI/Icon.h>
 #include <LibGUI/Menubar.h>
@@ -23,6 +24,9 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     auto app = TRY(GUI::Application::try_create(arguments));
 
+    TRY(Desktop::Launcher::add_allowed_handler_with_only_specific_urls("/bin/Help", { URL::create_with_file_protocol("/usr/share/man/man1/HexEditor.md") }));
+    TRY(Desktop::Launcher::seal_allowlist());
+
     Config::pledge_domain("HexEditor");
 
     auto app_icon = TRY(GUI::Icon::try_create_default_icon("app-hex-editor"sv));