diff --git a/Apps/Explorer/desk_server.vp b/Apps/Explorer/desk_server.vp
index eb0135a..5fb0bb8 100644
--- a/Apps/Explorer/desk_server.vp
+++ b/Apps/Explorer/desk_server.vp
@@ -192,6 +192,10 @@ class DeskServer:
     # 窗口移动/增删时连同阴影一起置脏（阴影超出窗口外框）
     def mark_win(self, y: int, h: int):
         self.mark(y - SHADOW_TOP, h + SHADOW_TOP + SHADOW_BOTTOM)
+        # 窗口画在任务栏之上，覆盖到底部条带时必须把任务栏一并置脏，否则残留旧内容。
+        tb: int = self.fb_h - TASKBAR_H
+        if y + h + SHADOW_BOTTOM > tb:
+            self.mark(tb, TASKBAR_H)
 
     # 活动窗口切换会改变标题栏配色：把所有窗口的标题栏行置脏
     def mark_titles(self):
@@ -662,6 +666,7 @@ class DeskServer:
             y += 1
 
     def render(self):
+        global _vblank_logged
         if self.dirty_any == 0: return
         y0: int = -1
         y1: int = -1