[gtk/cherry-pick-e941e2be] gdksurface-win32.c: Fix window menu positioning

[Chun-wei Fan <fanchunwei src gnome org>]

commit 9545ee34a7e20e285d34888c06bbc75673552e3e
Author: Chun-wei Fan <fanchunwei src gnome org>
Date:   Fri Mar 12 10:39:04 2021 +0000

    gdksurface-win32.c: Fix window menu positioning
    
    We ought to get the coordinates of where the window menu should be
    displayed using gdk_win32_surface_get_root_coords(), instead of rounding
    the position that we obtained with gdk_event_get_position().
    
    Also rename items a bit in the same function, and call
    gdk_event_get_event_type() for consistency with the other backends.
    
    Fixes issue #3704.
    
    
    (cherry picked from commit e941e2be7ded88728f41cdd03acd3381e45562b0)

 gdk/win32/gdksurface-win32.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)
---
diff --git a/gdk/win32/gdksurface-win32.c b/gdk/win32/gdksurface-win32.c
index c690fed206..7223c82bc7 100644
--- a/gdk/win32/gdksurface-win32.c
+++ b/gdk/win32/gdksurface-win32.c
@@ -4261,14 +4261,15 @@ gdk_win32_surface_is_win32 (GdkSurface *window)
 }
 
 static gboolean
-gdk_win32_surface_show_window_menu (GdkSurface *window,
-                                   GdkEvent  *event)
+gdk_win32_surface_show_window_menu (GdkSurface *surface,
+                                    GdkEvent  *event)
 {
   double event_x, event_y;
   int x, y;
-  GdkWin32Surface *impl = GDK_WIN32_SURFACE (window);
+  GdkWin32Surface *impl = GDK_WIN32_SURFACE (surface);
+  GdkEventType event_type = gdk_event_get_event_type (event);
 
-  switch ((int) event->event_type)
+  switch ((int) event_type)
     {
     case GDK_BUTTON_PRESS:
     case GDK_BUTTON_RELEASE:
@@ -4280,10 +4281,9 @@ gdk_win32_surface_show_window_menu (GdkSurface *window,
     }
 
   gdk_event_get_position (event, &event_x, &event_y);
-  x = round (event_x);
-  y = round (event_y);
+  gdk_win32_surface_get_root_coords (surface, event_x, event_y, &x, &y);
 
-  SendMessage (GDK_SURFACE_HWND (window),
+  SendMessage (GDK_SURFACE_HWND (surface),
                WM_SYSMENU,
                0,
                MAKELPARAM (x * impl->surface_scale, y * impl->surface_scale));