[PATCH 0/1] MR11133: win32u: Fix signed coordinate extraction in drag_drop_call.

[zhengyong chen (＠chenzhengyong)]

Xdnd protocol uses 16-bit signed coordinates for mouse position. When the cursor is on a secondary monitor left of the primary, coordinates are negative. LOWORD/HIWORD extract the low 16 bits as unsigned, causing sign loss when assigning to RECT fields.

Fix by casting LOWORD/HIWORD result to SHORT before assignment, ensuring proper sign extension on both 32-bit and 64-bit Wine.

Test on deepin v25 & UOS V20

-- 
https://gitlab.winehq.org/wine/wine/-/merge_requests/11133

[PATCH 1/1] win32u: Fix signed coordinate extraction in drag_drop_call.

[chenzhengyong]

From: chenzhengyong <[e-mail]>

Xdnd protocol uses 16-bit signed coordinates for mouse position.
When the cursor is on a secondary monitor left of the primary,
coordinates are negative. LOWORD/HIWORD extract the low 16 bits
as unsigned, causing sign loss when assigning to RECT fields.

Fix by casting LOWORD/HIWORD result to SHORT before assignment,
ensuring proper sign extension on both 32-bit and 64-bit Wine.

Signed-off-by: chenzhengyong <[e-mail]>
---
 dlls/win32u/clipboard.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/dlls/win32u/clipboard.c b/dlls/win32u/clipboard.c
index 4667d72e6ef..ec48cd09381 100644
--- a/dlls/win32u/clipboard.c
+++ b/dlls/win32u/clipboard.c
@@ -37,6 +37,9 @@
 
 WINE_DEFAULT_DEBUG_CHANNEL(clipboard);
 
+#define GET_X_LPARAM(lp) ((int)(short)LOWORD(lp))
+#define GET_Y_LPARAM(lp) ((int)(short)HIWORD(lp))
+
 static pthread_mutex_t clipboard_mutex = PTHREAD_MUTEX_INITIALIZER;
 
 struct cached_format
@@ -755,7 +758,7 @@ LRESULT drag_drop_call( HWND hwnd, UINT msg, WPARAM wparam, LPARAM lparam, void
         return KeUserModeCallback( NtUserDragDropLeave, 0, 0, &ret_ptr, &ret_len );
     case WINE_DRAG_DROP_DRAG:
     {
-        RECT rect = {LOWORD(wparam), HIWORD(wparam), LOWORD(wparam), HIWORD(wparam)};
+        RECT rect = {GET_X_LPARAM(wparam), GET_Y_LPARAM(wparam), GET_X_LPARAM(wparam), GET_Y_LPARAM(wparam)};
         struct drag_drop_drag_params params =
         {
             .hwnd = hwnd,
-- 
GitLab

https://gitlab.winehq.org/wine/wine/-/merge_requests/11133