LibGUI+WindowServer: Make it possible to have checkable GActions.

They show up as checkable GButtons in GToolBar, and with (or without) check
marks in menus.

There are a bunch of places to make use of this. This patch only takes
advantage of it in the FileManager for the view type actions.

LibGUI/GAction.cpp

@@ -106,3 +106,16 @@ void GAction::set_enabled(bool enabled)
         item.set_enabled(enabled);
     });
 }
+
+void GAction::set_checked(bool checked)
+{
+    if (m_checked == checked)
+        return;
+    m_checked = checked;
+    for_each_toolbar_button([checked] (GButton& button) {
+        button.set_checked(checked);
+    });
+    for_each_menu_item([checked] (GMenuItem& item) {
+        item.set_checked(checked);
+    });
+}

LibGUI/GAction.h

@@ -59,6 +59,12 @@ public:
     bool is_enabled() const { return m_enabled; }
     void set_enabled(bool);
 
+    bool is_checkable() const { return m_checkable; }
+    void set_checkable(bool checkable) { m_checkable = checkable; }
+
+    bool is_checked() const { ASSERT(is_checkable()); return m_checked; }
+    void set_checked(bool);
+
     void register_button(Badge<GButton>, GButton&);
     void unregister_button(Badge<GButton>, GButton&);
     void register_menu_item(Badge<GMenuItem>, GMenuItem&);
@@ -79,6 +85,8 @@ private:
     RetainPtr<GraphicsBitmap> m_icon;
     GShortcut m_shortcut;
     bool m_enabled { true };
+    bool m_checkable { false };
+    bool m_checked { false };
     ShortcutScope m_scope { ShortcutScope::None };
 
     HashTable<GButton*> m_buttons;

LibGUI/GButton.cpp

@@ -133,6 +133,9 @@ void GButton::set_action(GAction& action)
     m_action = action.make_weak_ptr();
     action.register_button({ }, *this);
     set_enabled(action.is_enabled());
+    set_checkable(action.is_checkable());
+    if (action.is_checkable())
+        set_checked(action.is_checked());
 }
 
 void GButton::set_icon(RetainPtr<GraphicsBitmap>&& icon)

LibGUI/GMenu.cpp

@@ -90,6 +90,9 @@ int GMenu::realize_menu()
             request.menu.menu_id = m_menu_id;
             request.menu.identifier = i;
             request.menu.enabled = action.is_enabled();
+            request.menu.checkable = action.is_checkable();
+            if (action.is_checkable())
+                request.menu.checked = action.is_checked();
             ASSERT(action.text().length() < (ssize_t)sizeof(request.text));
             strcpy(request.text, action.text().characters());
             request.text_length = action.text().length();

LibGUI/GMenuItem.cpp

@@ -16,6 +16,9 @@ GMenuItem::GMenuItem(unsigned menu_id, Retained<GAction>&& action)
 {
     m_action->register_menu_item({ }, *this);
     m_enabled = m_action->is_enabled();
+    m_checkable = m_action->is_checkable();
+    if (m_checkable)
+        m_checked = m_action->is_checked();
 }
 
 GMenuItem::~GMenuItem()
@@ -32,6 +35,15 @@ void GMenuItem::set_enabled(bool enabled)
     update_window_server();
 }
 
+void GMenuItem::set_checked(bool checked)
+{
+    ASSERT(is_checkable());
+    if (m_checked == checked)
+        return;
+    m_checked = checked;
+    update_window_server();
+}
+
 void GMenuItem::update_window_server()
 {
     auto& action = *m_action;
@@ -40,6 +52,9 @@ void GMenuItem::update_window_server()
     request.menu.menu_id = m_menu_id;
     request.menu.identifier = m_identifier;
     request.menu.enabled = action.is_enabled();
+    request.menu.checkable = action.is_checkable();
+    if (action.is_checkable())
+        request.menu.checked = action.is_checked();
     ASSERT(action.text().length() < (ssize_t)sizeof(request.text));
     strcpy(request.text, action.text().characters());
     request.text_length = action.text().length();

LibGUI/GMenuItem.h

@@ -20,6 +20,12 @@ public:
     GAction* action() { return m_action.ptr(); }
     unsigned identifier() const { return m_identifier; }
 
+    bool is_checkable() const { return m_checkable; }
+    void set_checkable(bool checkable) { m_checkable = checkable; }
+
+    bool is_checked() const { return m_checked; }
+    void set_checked(bool);
+
     bool is_enabled() const { return m_enabled; }
     void set_enabled(bool);
 
@@ -33,6 +39,8 @@ private:
     unsigned m_menu_id { 0 };
     unsigned m_identifier { 0 };
     bool m_enabled { true };
+    bool m_checkable { false };
+    bool m_checked { false };
     RetainPtr<GAction> m_action;
 };