Update Tabbable c'tor to allow member as top-level widget

Derived classes cannot use `Tabbable (_content_vbox,..)`
`_content_vbox` is a member of Tabbable (which has not
yet been initialized) at the point of construction.

This breaks internal API, hence the omnibus commit

gtk2_ardour/mixer_ui.cc

@@ -132,7 +132,7 @@ Mixer_UI::instance ()
 }
 
 Mixer_UI::Mixer_UI ()
-	: Tabbable (_content, _("Mixer"), X_("mixer"))
+	: Tabbable (_("Mixer"), X_("mixer"), &_content)
 	, plugin_search_clear_button (X_("Clear"))
 	, _mixer_scene_release (0)
 	, no_track_list_redisplay (false)

gtk2_ardour/public_editor.cc

@@ -33,7 +33,7 @@ ARDOUR::DataType PublicEditor::pbdid_dragged_dt = ARDOUR::DataType::NIL;
 
 PublicEditor::PublicEditor (Gtk::Widget& content)
 	: EditingContext (X_("Editor"))
-	, Tabbable (content, _("Editor"), X_("editor"))
+	, Tabbable (_("Editor"), X_("editor"), &content)
 {
 	_suspend_route_redisplay_counter.store (0);
 }

gtk2_ardour/rc_option_editor.cc

@@ -2363,7 +2363,7 @@ MidiPortOptions::pretty_name_edit (std::string const & path, string const & new_
 RCOptionEditor::RCOptionEditor ()
 	: OptionEditorContainer (Config)
 	  /* pack self-as-vbox into tabbable */
-	, Tabbable (*this, _("Preferences"), X_("preferences"), /* detached by default */ false)
+	, Tabbable (_("Preferences"), X_("preferences"), this, /* detached by default */ false)
 	, _rc_config (Config)
 	, _mixer_strip_visibility ("mixer-element-visibility")
 	, _cairo_image_surface (0)

gtk2_ardour/recorder_ui.cc

@@ -78,7 +78,7 @@ using namespace Menu_Helpers;
 #define PX_SCALE(px) std::max ((float)px, rintf ((float)px* UIConfiguration::instance ().get_ui_scale ()))
 
 RecorderUI::RecorderUI ()
-	: Tabbable (_content, _("Recorder"), X_("recorder"))
+	: Tabbable (_("Recorder"), X_("recorder"), &_content)
 	, _toolbar_sep (1.0)
 	, _btn_rec_all (_("All"))
 	, _btn_rec_none (_("None"))

gtk2_ardour/trigger_page.cc

@@ -65,7 +65,7 @@ using namespace Gtk;
 using namespace std;
 
 TriggerPage::TriggerPage ()
-	: Tabbable (_content, _("Cues"), X_("trigger"))
+	: Tabbable (_("Cues"), X_("trigger"), &_content)
 	, _cue_area_frame (0.5, 0, 1.0, 0)
 	, _cue_box (16, 16 * TriggerBox::default_triggers_per_box)
 	, _master_widget (16, 16)

libs/widgets/tabbable.cc

@@ -37,13 +37,17 @@ using namespace Gtk;
 using namespace Gtkmm2ext;
 using namespace ArdourWidgets;
 
-Tabbable::Tabbable (Gtk::Widget& w, const string& visible_name, string const & nontranslatable_name, bool tabbed_by_default)
+Tabbable::Tabbable (const string& visible_name, string const & nontranslatable_name, Widget* w, bool tabbed_by_default)
 	: WindowProxy (visible_name, nontranslatable_name)
-	, _contents (w)
 	, _parent_notebook (0)
 	, tab_requested_by_state (tabbed_by_default)
 {
-	default_layout ();
+	if (w) {
+		_contents = w;
+	} else {
+		_contents = &_content_vbox;
+		default_layout ();
+	}
 }
 
 Tabbable::~Tabbable ()
@@ -119,13 +123,13 @@ Tabbable::use_own_window (bool and_pack_it)
 	Gtk::Window* win = get (true);
 
 	if (and_pack_it) {
-		Gtk::Container* parent = _contents.get_parent();
+		Gtk::Container* parent = _contents->get_parent();
 		if (parent) {
-			_contents.hide ();
-			parent->remove (_contents);
+			_contents->hide ();
+			parent->remove (*_contents);
 		}
-		_own_notebook.append_page (_contents);
-		_contents.show ();
+		_own_notebook.append_page (*_contents);
+		_contents->show ();
 	}
 
 	return win;
@@ -179,7 +183,7 @@ Tabbable::get (bool create)
 void
 Tabbable::show_own_window (bool and_pack_it)
 {
-	Gtk::Widget* parent = _contents.get_parent();
+	Gtk::Widget* parent = _contents->get_parent();
 	Gtk::Allocation alloc;
 
 	if (parent) {
@@ -231,7 +235,7 @@ void
 Tabbable::change_visibility ()
 {
 	if (tabbed()) {
-		_parent_notebook->set_current_page (_parent_notebook->page_num (_contents));
+		_parent_notebook->set_current_page (_parent_notebook->page_num (*_contents));
 		return;
 	}
 
@@ -299,22 +303,22 @@ Tabbable::attach ()
 
 		save_pos_and_size ();
 
-		_contents.hide ();
-		_contents.get_parent()->remove (_contents);
+		_contents->hide ();
+		_contents->get_parent()->remove (*_contents);
 
 		/* leave the window around */
 
 		_window->hide ();
 	}
 
-	_parent_notebook->append_page (_contents);
-	_parent_notebook->set_tab_detachable (_contents);
-	_parent_notebook->set_tab_reorderable (_contents);
-	_parent_notebook->set_current_page (_parent_notebook->page_num (_contents));
+	_parent_notebook->append_page (*_contents);
+	_parent_notebook->set_tab_detachable (*_contents);
+	_parent_notebook->set_tab_reorderable (*_contents);
+	_parent_notebook->set_current_page (_parent_notebook->page_num (*_contents));
 
 	signal_tabbed_changed (true);
 
-	_contents.show ();
+	_contents->show ();
 
 	/* have to force this on, which is semantically correct, since
 	 * the user has effectively asked for it.
@@ -339,7 +343,7 @@ Tabbable::tabbed () const
 		return false;
 	}
 
-	if (_parent_notebook && (_parent_notebook->page_num (_contents) >= 0)) {
+	if (_parent_notebook && (_parent_notebook->page_num (*_contents) >= 0)) {
 		return true;
 	}
 
@@ -350,8 +354,8 @@ void
 Tabbable::hide_tab ()
 {
 	if (tabbed()) {
-		_contents.hide();
-		_parent_notebook->remove_page (_contents);
+		_contents->hide();
+		_parent_notebook->remove_page (*_contents);
 		StateChange (*this);
 	}
 }
@@ -360,12 +364,12 @@ void
 Tabbable::show_tab ()
 {
 	if (!window_visible() && _parent_notebook) {
-		if (_contents.get_parent() == 0) {
+		if (_contents->get_parent() == 0) {
 			tab_requested_by_state = true;
 			add_to_notebook (*_parent_notebook);
 		}
-		_parent_notebook->set_current_page (_parent_notebook->page_num (_contents));
-		_contents.show ();
+		_parent_notebook->set_current_page (_parent_notebook->page_num (*_contents));
+		_contents->show ();
 		current_toplevel()->present ();
 	}
 }

libs/widgets/widgets/tabbable.h

@@ -48,7 +48,7 @@ namespace ArdourWidgets {
 class LIBWIDGETS_API Tabbable : public Gtkmm2ext::WindowProxy
 {
 public:
-	Tabbable (Gtk::Widget&, const std::string& user_visible_name, std::string const & untranslated_name, bool tabbed_by_default = true);
+	Tabbable (const std::string& user_visible_name, std::string const & untranslated_name, Gtk::Widget* top = NULL, bool tabbed_by_default = true);
 	~Tabbable ();
 
 	void add_to_notebook (Gtk::Notebook& notebook);
@@ -58,7 +58,7 @@ public:
 	void attach ();
 	void detach ();
 
-	Gtk::Widget& contents() const { return _contents; }
+	Gtk::Widget& contents() const { return *_contents; }
 
 	/* this is where ArdourUI packs the tab switchers
 	 * (record/cues/edit/mix) into my toolbar area,
@@ -127,7 +127,6 @@ protected:
 	EventBoxExt         content_att_bottom;         /* a placeholder for the property box, if you want one */
 	/* clang-format on */
 
-
 	/* visibility controls */
 	ArdourWidgets::ArdourButton left_attachment_button;
 	ArdourWidgets::ArdourButton right_attachment_button;
@@ -143,7 +142,7 @@ private:
 	void window_unmapped ();
 
 	Gtk::VBox      _content_vbox; /* this is the root widget for a full-featured tabbable, which contains:  */
-	Gtk::Widget&   _contents; /* for most Tabbables this will be content_vbox;  but rc_options, for example, does something different. */
+	Gtk::Widget*   _contents; /* for most Tabbables this will be content_vbox;  but rc_options, for example, does something different. */
 	Gtk::Notebook  _own_notebook;
 	Gtk::Notebook* _parent_notebook;
 	bool            tab_requested_by_state;