From d2626f0c2a4d39a5d3f08594b422f8042003ce33 Mon Sep 17 00:00:00 2001
From: Mark Jansen <mark.jansen@reactos.org>
Date: Wed, 9 Jan 2019 22:27:41 +0100
Subject: [PATCH] [WIN32K:NTUSER] Find a better position for a menu that is
 off-screen Previously, we would just stick the menu on the edge of the
 screen. We should actually try to flip the menu around the point of origin,
 and only when that fails move it to the edge of the screen. CORE-15001
 CORE-9037

---
 win32ss/user/ntuser/menu.c | 34 ++++++++++++++++++++++++++++++----
 1 file changed, 30 insertions(+), 4 deletions(-)

diff --git a/win32ss/user/ntuser/menu.c b/win32ss/user/ntuser/menu.c
index 0dc6bac3759..b8177594df0 100644
--- a/win32ss/user/ntuser/menu.c
+++ b/win32ss/user/ntuser/menu.c
@@ -2911,9 +2911,22 @@ static BOOL FASTCALL MENU_ShowPopup(PWND pwndOwner, PMENU menu, UINT id, UINT fl
             x -= width - xanchor;
 
         if( x + width > monitor->rcMonitor.right)
-            x = monitor->rcMonitor.right - width;
+        {
+            /* If we would flip around our origin, would we go off screen on the other side? */
+            if (x - width < monitor->rcMonitor.left)
+                x = monitor->rcMonitor.right - width;
+            else
+                x -= width;
+        }
+    }
+    if( x < monitor->rcMonitor.left )
+    {
+        /* If we would flip around our origin, would we go off screen on the other side? */
+        if (x + width > monitor->rcMonitor.right)
+            x = monitor->rcMonitor.left;
+        else
+            x += width;
     }
-    if( x < monitor->rcMonitor.left ) x = monitor->rcMonitor.left;
 
     if( y + height > monitor->rcMonitor.bottom)
     {
@@ -2921,9 +2934,22 @@ static BOOL FASTCALL MENU_ShowPopup(PWND pwndOwner, PMENU menu, UINT id, UINT fl
             y -= height + yanchor;
 
         if( y + height > monitor->rcMonitor.bottom)
-            y = monitor->rcMonitor.bottom - height;
+        {
+            /* If we would flip around our origin, would we go off screen on the other side? */
+            if (y - height < monitor->rcMonitor.top)
+                y = monitor->rcMonitor.bottom - height;
+            else
+                y -= height;
+        }
+    }
+    if( y < monitor->rcMonitor.top )
+    {
+        /* If we would flip around our origin, would we go off screen on the other side? */
+        if (y + height > monitor->rcMonitor.bottom)
+            y = monitor->rcMonitor.top;
+        else
+            y += height;
     }
-    if( y < monitor->rcMonitor.top ) y = monitor->rcMonitor.top;
 
     pWnd = ValidateHwndNoErr( menu->hWnd );