From 87ea0d2ffab5244da0a93c74405d556c8d46ee05 Mon Sep 17 00:00:00 2001
From: Emmanuel Hansen <emmausssss@gmail.com>
Date: Tue, 18 Jun 2024 09:07:25 +0000
Subject: [PATCH] Win32 - set internal _shown flag if ShowWindow will make
 window visible (#16029)

* win32- set internal _shown flag if ShowWindow will make window visible

* check window visibility state from WM_WINDOWPOSCHANGED message
---
 src/Windows/Avalonia.Win32/WindowImpl.AppWndProc.cs | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/src/Windows/Avalonia.Win32/WindowImpl.AppWndProc.cs b/src/Windows/Avalonia.Win32/WindowImpl.AppWndProc.cs
index 737172943b7..29d4a614dea 100644
--- a/src/Windows/Avalonia.Win32/WindowImpl.AppWndProc.cs
+++ b/src/Windows/Avalonia.Win32/WindowImpl.AppWndProc.cs
@@ -790,6 +790,17 @@ protected virtual unsafe IntPtr AppWndProc(IntPtr hWnd, uint msg, IntPtr wParam,
                         return UiaCoreProviderApi.UiaReturnRawElementProvider(_hwnd, wParam, lParam, node);
                     }
                     break;
+                case WindowsMessage.WM_WINDOWPOSCHANGED:
+                    var winPos = Marshal.PtrToStructure<WINDOWPOS>(lParam);
+                    if((winPos.flags & (uint)SetWindowPosFlags.SWP_SHOWWINDOW) != 0)
+                    {
+                        _shown = true;
+                    }
+                    else if ((winPos.flags & (uint)SetWindowPosFlags.SWP_HIDEWINDOW) != 0)
+                    {
+                        _shown = false;
+                    }
+                    break;
             }
 
 #if USE_MANAGED_DRAG