change API for CairoWidget::focus_handler

This functor/closure is responsible for stealing focus from any existing text entry (or whatever else may have focus)
when clicking on a CairoWidget or derived class.

The old implementation just gave focus back to the editor canvas. The new version walks up the widget packing
heirarchy to find a focusable parent (from the CairoWidget for which it is invoked). If no focusable parent
is found, it cancels keyboard focus in the toplevel window containing the CairoWidget

gtk2_ardour/ardour_button.cc

@@ -724,7 +724,7 @@ ArdourButton::set_led_left (bool yn)
 bool
 ArdourButton::on_button_press_event (GdkEventButton *ev)
 {
-	focus_handler ();
+	focus_handler (this);
 
 	if (ev->button == 1 && (_elements & Indicator) && _led_rect && _distinct_led_click) {
 		if (ev->x >= _led_rect->x && ev->x < _led_rect->x + _led_rect->width &&

gtk2_ardour/big_clock_window.cc

@@ -55,8 +55,7 @@ void
 BigClockWindow::on_unmap ()
 {
 	ArdourWindow::on_unmap ();
-
-	PublicEditor::instance().reset_focus ();
+	PublicEditor::instance().reset_focus (&clock);
 }
 
 bool

gtk2_ardour/editor.cc

@@ -1178,7 +1178,7 @@ Editor::generic_event_handler (GdkEvent* ev)
 			/* leaving window, so reset focus, thus ending any and
 			   all text entry operations.
 			*/
-			reset_focus();
+			reset_focus (&contents());
 			break;
 		}
 		break;

gtk2_ardour/editor.h

@@ -1274,7 +1274,7 @@ class Editor : public PublicEditor, public PBD::ScopedConnectionList, public ARD
 
 	void naturalize_region ();
 
-	void reset_focus ();
+	void reset_focus (Gtk::Widget*);
 
 	void split_region ();
 

gtk2_ardour/editor_actions.cc

@@ -1739,9 +1739,40 @@ Editor::parameter_changed (std::string p)
 }
 
 void
-Editor::reset_focus ()
+Editor::reset_focus (Gtk::Widget* w)
 {
-	_track_canvas->grab_focus();
+	/* this resets focus to the first focusable parent of the given widget,
+	 * or, if there is no focusable parent, cancels focus in the toplevel
+	 * window that the given widget is packed into (if there is one).
+	 */
+
+	if (!w) {
+		return;
+	}
+
+	Gtk::Widget* top = w->get_toplevel();
+
+	if (!top || !top->is_toplevel()) {
+		return;
+	}
+
+	w = w->get_parent ();
+
+	while (w) {
+		if (w->get_can_focus ()) {
+			Window* win = dynamic_cast<Window*> (top);
+			win->set_focus (*w);
+			return;
+		}
+		w = w->get_parent ();
+	}
+
+	/* no focusable parent found, cancel focus in top level window.
+	   C++ API cannot be used for this. Thanks, references.
+	 */
+
+	gtk_window_set_focus (GTK_WINDOW(top->gobj()), 0);
+
 }
 
 void

gtk2_ardour/editor_mouse.cc

@@ -2456,7 +2456,7 @@ Editor::escape ()
 		selection->clear ();
 	}
 
-	reset_focus ();
+	reset_focus (&contents());
 }
 
 /** Update _join_object_range_state which indicate whether we are over the top

gtk2_ardour/public_editor.h

@@ -319,7 +319,7 @@ class PublicEditor : public Gtkmm2ext::Tabbable {
 	Glib::RefPtr<Gtk::ActionGroup> editor_menu_actions;
 	Glib::RefPtr<Gtk::ActionGroup> _region_actions;
 
-	virtual void reset_focus () = 0;
+	virtual void reset_focus (Gtk::Widget*) = 0;
 
 	virtual bool canvas_scroll_event (GdkEventScroll* event, bool from_canvas) = 0;
 	virtual bool canvas_control_point_event (GdkEvent* event, ArdourCanvas::Item*, ControlPoint*) = 0;

libs/gtkmm2ext/cairo_widget.cc

@@ -30,7 +30,7 @@ static const char* has_cairo_widget_background_info = "has_cairo_widget_backgrou
 bool CairoWidget::_flat_buttons = false;
 bool CairoWidget::_widget_prelight = true;
 
-sigc::slot<void> CairoWidget::focus_handler;
+sigc::slot<void,Gtk::Widget*> CairoWidget::focus_handler;
 
 void CairoWidget::set_source_rgb_a( cairo_t* cr, Gdk::Color col, float a)  //ToDo:  this one and the Canvas version should be in a shared file (?)
 {
@@ -60,7 +60,7 @@ CairoWidget::~CairoWidget ()
 bool
 CairoWidget::on_button_press_event (GdkEventButton*)
 {
-	focus_handler();
+	focus_handler (this);
 	return false;
 }
 
@@ -393,7 +393,7 @@ CairoWidget::set_widget_prelight (bool yn)
 }
 
 void
-CairoWidget::set_focus_handler (sigc::slot<void> s)
+CairoWidget::set_focus_handler (sigc::slot<void,Gtk::Widget*> s)
 {
 	focus_handler = s;
 }

libs/gtkmm2ext/gtkmm2ext/cairo_widget.h

@@ -93,7 +93,7 @@ public:
 	   they wish to invoke any existing focus handler from their own
 	   button press handler, they can just use: focus_handler();
 	*/
-	static void set_focus_handler (sigc::slot<void>);
+	static void set_focus_handler (sigc::slot<void,Gtk::Widget*>);
 
 protected:
 	/** Render the widget to the given Cairo context */
@@ -118,7 +118,7 @@ protected:
 	static bool	_widget_prelight;
 	bool		_grabbed;
 
-	static sigc::slot<void> focus_handler;
+	static sigc::slot<void,Gtk::Widget*> focus_handler;
 
   private:
 	Cairo::RefPtr<Cairo::Surface> image_surface;