MP Lobby: use exit hook for quit confirmation

By design, this extends the confirmation popup to exiting the lobby with the Log Out button too (previously, only
the Esc key triggered it. However, given the proximity of the button to other control buttons, it's not inconceivable
that someone might click it by accident, so the confirmation is useful.

src/gui/dialogs/lobby/lobby.cpp

@@ -654,16 +654,13 @@ void lobby_main::update_selected_game()
 	player_list_dirty_ = true;
 }
 
-void lobby_main::signal_handler_key_down(SDL_Keycode key, bool& handled, bool& halt)
+bool lobby_main::exit_hook(window& window)
 {
-	if(key == SDLK_ESCAPE) {
-		if(quit()) {
-			window_->set_retval(window::OK);
-			window_->close();
-		}
-		handled = true;
-		halt = true;
+	if(window.get_retval() == window::CANCEL) {
+		return quit();
 	}
+
+	return true;
 }
 
 void lobby_main::pre_show(window& window)
@@ -694,12 +691,9 @@ void lobby_main::pre_show(window& window)
 			std::bind(&lobby_main::player_filter_callback, this, _1));
 
 	window.set_enter_disabled(true);
-	window.set_escape_disabled(true);
 
-	// A new key handler to deal with escape in a different manner.
-	window.connect_signal<event::SDL_KEY_DOWN>(
-		std::bind(&lobby_main::signal_handler_key_down, this, _5, _3, _4),
-		event::dispatcher::front_pre_child);
+	// Exit hook to add a confirmation when quitting the Lobby.
+	window.set_exit_hook(std::bind(&lobby_main::exit_hook, this, std::ref(window)));
 
 	window_ = &window;
 

src/gui/dialogs/lobby/lobby.hpp

@@ -158,7 +158,7 @@ class lobby_main : public modal_dialog, public quit_confirmation, private plugin
 
 	void skip_replay_changed_callback(window& window);
 
-	void signal_handler_key_down(SDL_Keycode key, bool& handled, bool& halt);
+	bool exit_hook(window& window);
 
 	static bool logout_prompt();