Make title screen rebuild its layout when the window is resized

This also restores one of the two reverted title screen tweaks.

data/gui/widget/panel_title_screen.cfg

@@ -75,6 +75,7 @@
 	id = "title_screen"
 	description = "Definition of the panel for the title screen"
 
+	{_GUI_RESOLUTION (window_width,window_height = 850, 650) 10 5 10 5}
 	{_GUI_RESOLUTION () 25 5 9 14 }
 
 [/panel_definition]

src/gui/dialogs/title_screen.cpp

@@ -362,6 +362,14 @@ void ttitle_screen::pre_show(twindow& window)
 	if(cores.size() <= 1) {
 		find_widget<tbutton>(&window, "cores", false).set_visible(twindow::tvisible::invisible);
 	}
+
+	window.connect_signal<event::SDL_VIDEO_RESIZE>(std::bind(&ttitle_screen::on_resize, this, std::ref(window)));
+}
+
+void ttitle_screen::on_resize(twindow& window)
+{
+	window.set_retval(NOTHING);
+	window.close();
 }
 
 void ttitle_screen::update_tip(twindow& window, const bool previous)

src/gui/dialogs/title_screen.hpp

@@ -91,6 +91,8 @@ private:
 	/** Inherited from tdialog. */
 	void pre_show(twindow& window);
 
+	void on_resize(twindow& window);
+
 	/** Holds the debug clock dialog. */
 	tpopup* debug_clock_;
 

src/wesnoth.cpp

@@ -854,6 +854,8 @@ static int do_gameloop(const std::vector<std::string>& args)
 		} else if(res == gui2::ttitle_screen::START_MAP_EDITOR) {
 			game->start_editor();
 			continue;
+		} else if(res == gui2::ttitle_screen::NOTHING) {
+			continue;
 		}
 		game->launch_game(should_reload);
 	}