Function step_detach_layer

UnitTests/UnitTest_AttachDetach/DemoKeeper.cpp:75–82

	}

	static void step_detach_layer()
	{
		MyGUI::Widget* widget = get_random(all_widgets);
		if (!widget)
			return;
		MyGUI::LayerManager::getInstance().detachFromLayer(widget);
		test_widgets();
	}

	static void step_detach_layer(int _count)
	{