[PATCH 0/2] MR8035: misc: Fix two instances where the thread DPI awareness context is not saved/restored.

[Conor McCarthy (＠cmccarthy)]

I'm pretty sure the user32 patch fixes a bug, but there may be a reason I'm not aware of for not saving/restoring in win32u `process_mouse_message()`.

[PATCH 1/2] user32: Restore the previous thread DPI awareness context before leaving CalcChildScroll().

[Conor McCarthy]

From: Conor McCarthy

---
 dlls/user32/mdi.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/dlls/user32/mdi.c b/dlls/user32/mdi.c
index 05725a29914..f023eb5e39d 100644
--- a/dlls/user32/mdi.c
+++ b/dlls/user32/mdi.c
@@ -1658,7 +1658,7 @@ void WINAPI CalcChildScroll( HWND hwnd, INT scroll )
             {
                 HeapFree( GetProcessHeap(), 0, list );
                 NtUserShowScrollBar( hwnd, SB_BOTH, FALSE );
-                return;
+                goto done;
             }
             if (style & WS_VISIBLE)
             {
@@ -1700,6 +1700,8 @@ void WINAPI CalcChildScroll( HWND hwnd, INT scroll )
                         }
    		break;
     }
+
+done:
     SetThreadDpiAwarenessContext( context );
 }

[PATCH 2/2] win32u: Restore the previous thread DPI awareness context before leaving process_mouse_message().

[Conor McCarthy]

From: Conor McCarthy

---
 dlls/win32u/message.c | 24 ++++++++++++++----------
 1 file changed, 14 insertions(+), 10 deletions(-)

diff --git a/dlls/win32u/message.c b/dlls/win32u/message.c
index a6fa5c3c0ba..f1e6ca132ce 100644
--- a/dlls/win32u/message.c
+++ b/dlls/win32u/message.c
@@ -2507,8 +2507,9 @@ static BOOL process_mouse_message( MSG *msg, UINT hw_id, ULONG_PTR extra_info, H
     EVENTMSG event;
     GUITHREADINFO info;
     MOUSEHOOKSTRUCTEX hook;
-    BOOL eat_msg;
+    BOOL eat_msg = TRUE;
     WPARAM wparam;
+    UINT context;

/* find the window to dispatch this mouse message to */

@@ -2541,7 +2542,7 @@ static BOOL process_mouse_message( MSG *msg, UINT hw_id, ULONG_PTR extra_info, H
     }

msg->pt = point_phys_to_win_dpi( msg->hwnd, msg->pt );
-    set_thread_dpi_awareness_context( get_window_dpi_awareness_context( msg->hwnd ));
+    context = set_thread_dpi_awareness_context( get_window_dpi_awareness_context( msg->hwnd ));

/* FIXME: is this really the right place for this hook? */
     event.message = msg->message;
@@ -2551,7 +2552,7 @@ static BOOL process_mouse_message( MSG *msg, UINT hw_id, ULONG_PTR extra_info, H
     event.paramH  = msg->pt.y;
     call_hooks( WH_JOURNALRECORD, HC_ACTION, 0, (LPARAM)&event, sizeof(event) );

-    if (!check_hwnd_filter( msg, hwnd_filter )) return FALSE;
+    if (!check_hwnd_filter( msg, hwnd_filter )) goto done;

pt = msg->pt;
     message = msg->message;
@@ -2606,13 +2607,13 @@ static BOOL process_mouse_message( MSG *msg, UINT hw_id, ULONG_PTR extra_info, H
                }
            }
         }
-        if (message < first || message > last) return FALSE;
+        if (message < first || message > last) goto done;
         /* update static double click conditions */
         if (update) clk_msg = *msg;
     }
     else
     {
-        if (message < first || message > last) return FALSE;
+        if (message < first || message > last) goto done;
     }
     msg->wParam = wparam;

@@ -2632,26 +2633,26 @@ static BOOL process_mouse_message( MSG *msg, UINT hw_id, ULONG_PTR extra_info, H
         hook.mouseData    = msg->wParam;
         accept_hardware_message( hw_id );
         call_hooks( WH_CBT, HCBT_CLICKSKIPPED, message, (LPARAM)&hook, sizeof(hook) );
-        return FALSE;
+        goto done;
     }

if ((hittest == HTERROR) || (hittest == HTNOWHERE))
     {
         send_message( msg->hwnd, WM_SETCURSOR, (WPARAM)msg->hwnd, MAKELONG( hittest, msg->message ));
         accept_hardware_message( hw_id );
-        return FALSE;
+        goto done;
     }

if (remove) accept_hardware_message( hw_id );

+    eat_msg = FALSE;
+
     if (!remove || info.hwndCapture)
     {
         msg->message = message;
-        return TRUE;
+        goto done;
     }

-    eat_msg = FALSE;
-
     if (msg->message == WM_LBUTTONDOWN ||
         msg->message == WM_RBUTTONDOWN ||
         msg->message == WM_MBUTTONDOWN ||
@@ -2702,6 +2703,9 @@ static BOOL process_mouse_message( MSG *msg, UINT hw_id, ULONG_PTR extra_info, H
     send_message( msg->hwnd, WM_SETCURSOR, (WPARAM)msg->hwnd, MAKELONG( hittest, msg->message ));

msg->message = message;
+
+done:
+    set_thread_dpi_awareness_context( context );
     return !eat_msg;
 }

[Rémi Bernon (＠rbernon)]

The `process_mouse_message` change isn't necessary because it's being called from `process_hardware_message` which already changes and restores the thread DPI context.