LibGUI+WindowServer: Add "visible" state to GUI actions

This patch adds a visibility state to GUI::Action. All actions default
to being visible. When invisible, they do not show up in toolbars on
menus (and importantly, they don't occupy any space).

This can be used to hide/show context-sensitive actions dynamically
without rebuilding menus and toolbars.

Thanks to Tim Slater for assuming that action visibility was a thing,
which gave me a reason to implement it! :^)

Userland/Libraries/LibGUI/Action.cpp

@@ -228,6 +228,19 @@ void Action::set_enabled(bool enabled)
     });
 }
 
+void Action::set_visible(bool visible)
+{
+    if (m_visible == visible)
+        return;
+    m_visible = visible;
+    for_each_toolbar_button([visible](auto& button) {
+        button.set_visible(visible);
+    });
+    for_each_menu_item([visible](auto& item) {
+        item.set_visible(visible);
+    });
+}
+
 void Action::set_checked(bool checked)
 {
     if (m_checked == checked)

Userland/Libraries/LibGUI/Action.h

@@ -105,6 +105,9 @@ public:
     bool is_enabled() const { return m_enabled; }
     void set_enabled(bool);
 
+    bool is_visible() const { return m_visible; }
+    void set_visible(bool);
+
     bool is_checkable() const { return m_checkable; }
     void set_checkable(bool checkable) { m_checkable = checkable; }
 
@@ -146,6 +149,7 @@ private:
     Shortcut m_shortcut;
     Shortcut m_alternate_shortcut;
     bool m_enabled { true };
+    bool m_visible { true };
     bool m_checkable { false };
     bool m_checked { false };
     bool m_swallow_key_event_when_disabled { false };

Userland/Libraries/LibGUI/Button.cpp

@@ -165,6 +165,7 @@ void Button::set_action(Action& action)
 {
     m_action = action;
     action.register_button({}, *this);
+    set_visible(action.is_visible());
     set_enabled(action.is_enabled());
     set_checkable(action.is_checkable());
     if (action.is_checkable())

Userland/Libraries/LibGUI/Menu.cpp

@@ -201,14 +201,14 @@ void Menu::realize_menu_item(MenuItem& item, int item_id)
         bool exclusive = action.group() && action.group()->is_exclusive() && action.is_checkable();
         bool is_default = (m_current_default_action.ptr() == &action);
         auto icon = action.icon() ? action.icon()->to_shareable_bitmap() : Gfx::ShareableBitmap();
-        ConnectionToWindowServer::the().async_add_menu_item(m_menu_id, item_id, -1, action.text(), action.is_enabled(), action.is_checkable(), action.is_checkable() ? action.is_checked() : false, is_default, shortcut_text, icon, exclusive);
+        ConnectionToWindowServer::the().async_add_menu_item(m_menu_id, item_id, -1, action.text(), action.is_enabled(), action.is_visible(), action.is_checkable(), action.is_checkable() ? action.is_checked() : false, is_default, shortcut_text, icon, exclusive);
         break;
     }
     case MenuItem::Type::Submenu: {
         auto& submenu = *item.submenu();
         submenu.realize_if_needed(m_current_default_action.strong_ref());
         auto icon = submenu.icon() ? submenu.icon()->to_shareable_bitmap() : Gfx::ShareableBitmap();
-        ConnectionToWindowServer::the().async_add_menu_item(m_menu_id, item_id, submenu.menu_id(), submenu.name(), true, false, false, false, "", icon, false);
+        ConnectionToWindowServer::the().async_add_menu_item(m_menu_id, item_id, submenu.menu_id(), submenu.name(), true, true, false, false, false, "", icon, false);
         break;
     }
     case MenuItem::Type::Invalid:

Userland/Libraries/LibGUI/MenuItem.cpp

@@ -50,6 +50,14 @@ void MenuItem::set_enabled(bool enabled)
     update_window_server();
 }
 
+void MenuItem::set_visible(bool visible)
+{
+    if (m_visible == visible)
+        return;
+    m_visible = visible;
+    update_window_server();
+}
+
 void MenuItem::set_checked(bool checked)
 {
     VERIFY(is_checkable());
@@ -75,7 +83,7 @@ void MenuItem::update_window_server()
     auto& action = *m_action;
     auto shortcut_text = action.shortcut().is_valid() ? action.shortcut().to_deprecated_string() : DeprecatedString();
     auto icon = action.icon() ? action.icon()->to_shareable_bitmap() : Gfx::ShareableBitmap();
-    ConnectionToWindowServer::the().async_update_menu_item(m_menu_id, m_identifier, -1, action.text(), action.is_enabled(), action.is_checkable(), action.is_checkable() ? action.is_checked() : false, m_default, shortcut_text, icon);
+    ConnectionToWindowServer::the().async_update_menu_item(m_menu_id, m_identifier, -1, action.text(), action.is_enabled(), action.is_visible(), action.is_checkable(), action.is_checkable() ? action.is_checked() : false, m_default, shortcut_text, icon);
 }
 
 void MenuItem::set_menu_id(Badge<Menu>, unsigned int menu_id)

Userland/Libraries/LibGUI/MenuItem.h

@@ -45,6 +45,9 @@ public:
     bool is_enabled() const { return m_enabled; }
     void set_enabled(bool);
 
+    bool is_visible() const { return m_visible; }
+    void set_visible(bool);
+
     bool is_default() const { return m_default; }
     void set_default(bool);
 
@@ -61,6 +64,7 @@ private:
     int m_menu_id { -1 };
     unsigned m_identifier { 0 };
     bool m_enabled { true };
+    bool m_visible { true };
     bool m_checkable { false };
     bool m_checked { false };
     bool m_default { false };