diff --git a/src/backend/x11/event.c b/src/backend/x11/event.c
index 60aa757..fd6c9f3 100644
--- a/src/backend/x11/event.c
+++ b/src/backend/x11/event.c
@@ -492,7 +492,8 @@ bool backend_poll_event(backend_t *backend, event_t *event) {
   auto raw_event = xcb_poll_for_event(backend->conn);
   if (!raw_event) return false;
 
-  return handle_event(backend, raw_event, event);
+  handle_event(backend, raw_event, event);
+  return true;
 }
 
 bool backend_next_event(backend_t *backend, event_t *event) {
diff --git a/src/core/backend.h b/src/core/backend.h
index 36d5238..ac15d50 100644
--- a/src/core/backend.h
+++ b/src/core/backend.h
@@ -21,6 +21,16 @@ backend_detect_t *backend_detect(backend_t *backend);
 void backend_detect_destroy(backend_detect_t *detect);
 
 int backend_get_fd(backend_t *backend);
+
+/**
+ * @brief 非阻塞地从 backend 中读取下一个归一化的事件
+ *
+ * @details
+ * 1. 函数立即返回
+ * 2. 只要取到了事件，函数就返回 true ，事件填充到 event 参数中
+ *
+ * @returns 如果还有下一个事件待读取，返回 true ，否则返回 false
+ */
 bool backend_poll_event(backend_t *backend, event_t *event);
 
 /**
diff --git a/src/core/event.c b/src/core/event.c
index f933eae..693a126 100644
--- a/src/core/event.c
+++ b/src/core/event.c
@@ -4,7 +4,7 @@
 #include "core/window.h"
 
 void event_cleanup(event_t *event) {
-  if (!event) return;
+  if (!event || event->type == ZDWM_EVENT_NONE) return;
 
   switch (event->type) {
   case ZDWM_EVENT_WINDOW_MAP_REQUEST:
diff --git a/src/core/event.h b/src/core/event.h
index a2b7adf..1ef45fb 100644
--- a/src/core/event.h
+++ b/src/core/event.h
@@ -6,6 +6,7 @@
 #include "core/window.h"
 
 typedef enum event_type_t {
+  ZDWM_EVENT_NONE,
   ZDWM_EVENT_KEY_PRESS,
   ZDWM_EVENT_POINTER_BUTTON_PRESS,
   ZDWM_EVENT_POINTER_BUTTON_RELEASE,