Merge pull request #24149 from nullaus/v2.1

Merge pull request #23874 from nullaus/bug1044125 a=fabrice
(cherry picked from commit f1d3cd2301b604b7b8b8dcf69bd36ba638c1ab44)

Conflicts:
	apps/system/js/action_menu.js
	apps/system/js/app_transition_controller.js
	apps/system/js/app_window.js
	apps/system/js/app_window_manager.js
	apps/system/js/keyboard_manager.js
	apps/system/js/statusbar.js
	apps/system/js/value_selector/value_selector.js
	apps/system/test/unit/action_menu_test.js
	apps/system/test/unit/app_transition_controller_test.js
	apps/system/test/unit/app_window_test.js
	apps/system/test/unit/statusbar_test.js
	apps/system/test/unit/value_selector_test.js
There is no _hidewindow handler