diff --git a/Packages/vChewing_TooltipUI/Sources/TooltipUI/TooltipUI.swift b/Packages/vChewing_TooltipUI/Sources/TooltipUI/TooltipUI.swift
index 6654ab7f..54cee25b 100644
--- a/Packages/vChewing_TooltipUI/Sources/TooltipUI/TooltipUI.swift
+++ b/Packages/vChewing_TooltipUI/Sources/TooltipUI/TooltipUI.swift
@@ -41,6 +41,7 @@ public class TooltipUI: NSWindowController {
     messageText = NSAttributedTooltipTextView()
     messageText.backgroundColor = NSColor.controlBackgroundColor
     messageText.textColor = NSColor.textColor
+    messageText.needsDisplay = true
     panel.contentView?.addSubview(messageText)
     super.init(window: panel)
   }