PixelPaint: Adjust menu ampersand shortcut characters

A few of the menu items were missing shortcut characters completely,
so in the interest of keyboard navigation some have been added (even
if they are not ideal).

In a few menus, severals actions had the same menu shortcut, so the
later ones were not accessible through it. These have also been
differentiated.

Userland/Applications/PixelPaint/MainWidget.cpp

@@ -255,7 +255,7 @@ void MainWidget::initialize_menubar(GUI::Window& window)
 
     edit_menu.add_separator();
     edit_menu.add_action(GUI::Action::create(
-        "&Swap Colors", { Mod_None, Key_X }, [&](auto&) {
+        "S&wap Colors", { Mod_None, Key_X }, [&](auto&) {
             auto* editor = current_image_editor();
             if (!editor)
                 return;
@@ -316,7 +316,7 @@ void MainWidget::initialize_menubar(GUI::Window& window)
         });
 
     m_add_guide_action = GUI::Action::create(
-        "Add Guide", [&](auto&) {
+        "&Add Guide", [&](auto&) {
             auto dialog = PixelPaint::EditGuideDialog::construct(&window);
             if (dialog->exec() != GUI::Dialog::ExecOK)
                 return;
@@ -330,7 +330,7 @@ void MainWidget::initialize_menubar(GUI::Window& window)
 
     // Save this so other methods can use it
     m_show_guides_action = GUI::Action::create_checkable(
-        "Show Guides", [&](auto& action) {
+        "Show &Guides", [&](auto& action) {
             Config::write_bool("PixelPaint", "Guides", "Show", action.is_checked());
             if (auto* editor = current_image_editor()) {
                 editor->set_guide_visibility(action.is_checked());
@@ -351,14 +351,14 @@ void MainWidget::initialize_menubar(GUI::Window& window)
     view_menu.add_action(*m_show_guides_action);
 
     view_menu.add_action(GUI::Action::create(
-        "Clear Guides", [&](auto&) {
+        "&Clear Guides", [&](auto&) {
             if (auto* editor = current_image_editor())
                 editor->clear_guides();
         }));
     view_menu.add_separator();
 
     auto show_pixel_grid_action = GUI::Action::create_checkable(
-        "Show Pixel Grid", [&](auto& action) {
+        "Show &Pixel Grid", [&](auto& action) {
             Config::write_bool("PixelPaint", "PixelGrid", "Show", action.is_checked());
             if (auto* editor = current_image_editor())
                 editor->set_pixel_grid_visibility(action.is_checked());
@@ -367,7 +367,7 @@ void MainWidget::initialize_menubar(GUI::Window& window)
     view_menu.add_action(*show_pixel_grid_action);
 
     m_show_rulers_action = GUI::Action::create_checkable(
-        "Show Rulers", { Mod_Ctrl, Key_R }, [&](auto& action) {
+        "Show R&ulers", { Mod_Ctrl, Key_R }, [&](auto& action) {
             Config::write_bool("PixelPaint", "Rulers", "Show", action.is_checked());
             if (auto* editor = current_image_editor()) {
                 editor->set_ruler_visibility(action.is_checked());
@@ -458,7 +458,7 @@ void MainWidget::initialize_menubar(GUI::Window& window)
             m_layer_list_widget->select_top_layer();
         }));
     layer_menu.add_action(GUI::Action::create(
-        "Select &Bottom Layer", { 0, Key_End }, [&](auto&) {
+        "Select B&ottom Layer", { 0, Key_End }, [&](auto&) {
             m_layer_list_widget->select_bottom_layer();
         }));
     layer_menu.add_separator();
@@ -531,7 +531,7 @@ void MainWidget::initialize_menubar(GUI::Window& window)
     };
     layer_menu.add_separator();
     layer_menu.add_action(GUI::Action::create(
-        "&Flatten Image", { Mod_Ctrl, Key_F }, [&](auto&) {
+        "Fl&atten Image", { Mod_Ctrl, Key_F }, [&](auto&) {
             auto* editor = current_image_editor();
             if (!editor)
                 return;