Declare window property on SDL_Event class

Author: santiagolizardo

src/event.c

@@ -288,6 +288,7 @@ PHP_MINIT_FUNCTION(sdl_event)
 	zend_declare_property_null(php_sdl_event_ce, ZEND_STRL("type"), ZEND_ACC_PUBLIC);
 	zend_declare_property_null(php_sdl_event_ce, ZEND_STRL("key"), ZEND_ACC_PUBLIC);
 	zend_declare_property_null(php_sdl_event_ce, ZEND_STRL("motion"), ZEND_ACC_PUBLIC);
+	zend_declare_property_null(php_sdl_event_ce, ZEND_STRL("window"), ZEND_ACC_PUBLIC);
 
 	return SUCCESS;
 }