From e118805eefc9a64b8deedf9ad9e96b90c1c0a68e Mon Sep 17 00:00:00 2001
From: Vincent Wei <vincent@minigui.org>
Date: Sat, 16 Sep 2023 15:43:07 +0800
Subject: [PATCH] fix a bug of GetUpdateRect: intersect bouding rectangle of
 invalid region with client rect

---
 src/gui/window.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/gui/window.c b/src/gui/window.c
index 556a6330..d5849462 100644
--- a/src/gui/window.c
+++ b/src/gui/window.c
@@ -5585,11 +5585,13 @@ BOOL GUIAPI ValidateRegion (HWND hWnd, const CLIPRGN* pRgn)
 BOOL GUIAPI GetUpdateRect (HWND hWnd, RECT* update_rect)
 {
     PMAINWIN pWin;
+    RECT rcClient;
 
     MG_CHECK_RET (MG_IS_NORMAL_WINDOW(hWnd), FALSE);
     pWin = MG_GET_WINDOW_PTR (hWnd);
 
-    *update_rect = pWin->InvRgn.rgn.rcBound;
+    GetClientRect(hWnd, &rcClient);
+    IntersectRect(update_rect, &pWin->InvRgn.rgn.rcBound, &rcClient);
     return TRUE;
 }