mute system beep on alt+key press

.gitignore

@@ -196,3 +196,12 @@ ModuleCache.noindex/
 Build/Intermediates.noindex/
 info.plist
 build-intermediate
+
+
+##################
+# Vim
+##################
+.vim
+coc-settings.json
+.ccls-cache
+.ccls

src/Windows/Avalonia.Win32/Interop/UnmanagedMethods.cs

@@ -607,6 +607,14 @@ namespace Avalonia.Win32.Interop
             GWL_USERDATA = -21
         }
 
+        public enum MenuCharParam
+        {
+            MNC_IGNORE = 0,
+            MNC_CLOSE = 1,
+            MNC_EXECUTE = 2,
+            MNC_SELECT = 3
+        }
+
         [StructLayout(LayoutKind.Sequential)]
         public struct RGBQUAD
         {

src/Windows/Avalonia.Win32/WindowImpl.cs

@@ -498,6 +498,10 @@ namespace Avalonia.Win32
                             KeyInterop.KeyFromVirtualKey(ToInt32(wParam)), WindowsKeyboardDevice.Instance.Modifiers);
                     break;
 
+                case UnmanagedMethods.WindowsMessage.WM_MENUCHAR:
+                    // mute the system beep
+                    return (IntPtr)((Int32)UnmanagedMethods.MenuCharParam.MNC_CLOSE << 16);
+
                 case UnmanagedMethods.WindowsMessage.WM_KEYUP:
                 case UnmanagedMethods.WindowsMessage.WM_SYSKEYUP:
                     e = new RawKeyEventArgs(