implement disabling app delegate.

native/Avalonia.Native/src/OSX/app.mm

@@ -95,11 +95,14 @@ ComPtr<IAvnApplicationEvents> _events;
 }
 @end
 
-extern void InitializeAvnApp(IAvnApplicationEvents* events)
+extern void InitializeAvnApp(IAvnApplicationEvents* events, bool disableAppDelegate)
 {
-    NSApplication* app = [AvnApplication sharedApplication];
-    id delegate = [[AvnAppDelegate alloc] initWithEvents:events];
-    [app setDelegate:delegate];
+    if(!disableAppDelegate)
+    {
+        NSApplication* app = [AvnApplication sharedApplication];
+        id delegate = [[AvnAppDelegate alloc] initWithEvents:events];
+        [app setDelegate:delegate];
+    }
 }
 
 HRESULT AvnApplicationCommands::HideApp()

native/Avalonia.Native/src/OSX/common.h

@@ -32,7 +32,7 @@ extern void SetServicesMenu (IAvnMenu* menu);
 extern IAvnMenu* GetAppMenu ();
 extern NSMenuItem* GetAppMenuItem ();
 
-extern void InitializeAvnApp(IAvnApplicationEvents* events);
+extern void InitializeAvnApp(IAvnApplicationEvents* events, bool disableAppDelegate);
 extern NSApplicationActivationPolicy AvnDesiredActivationPolicy;
 extern NSPoint ToNSPoint (AvnPoint p);
 extern NSRect ToNSRect (AvnRect r);

native/Avalonia.Native/src/OSX/main.mm

@@ -4,6 +4,7 @@
 
 static NSString* s_appTitle = @"Avalonia";
 static int disableSetProcessName = 0;
+static bool disableAppDelegate = false;
 
 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
@@ -151,6 +152,16 @@ public:
         }
     }
     
+    virtual HRESULT SetDisableAppDelegate(int disable) override
+    {
+        START_COM_CALL;
+        
+        @autoreleasepool {
+            disableAppDelegate = disable;
+            return S_OK;
+        }
+    }
+    
 };
 
 /// See "Using POSIX Threads in a Cocoa Application" section here:
@@ -193,7 +204,7 @@ public:
         @autoreleasepool{
             [[ThreadingInitializer new] do];
         }
-        InitializeAvnApp(events);
+        InitializeAvnApp(events, disableAppDelegate);
         return S_OK;
     };
     

src/Avalonia.Native/AvaloniaNativePlatform.cs

@@ -103,6 +103,7 @@ namespace Avalonia.Native
 
                 _factory.MacOptions.SetShowInDock(macOpts.ShowInDock ? 1 : 0);
                 _factory.MacOptions.SetDisableSetProcessName(macOpts.DisableSetProcessName ? 1 : 0);
+                _factory.MacOptions.SetDisableAppDelegate(macOpts.DisableAvaloniaAppDelegate ? 1 : 0);
             }
 
             AvaloniaLocator.CurrentMutable

src/Avalonia.Native/AvaloniaNativePlatformExtensions.cs

@@ -85,5 +85,11 @@ namespace Avalonia
         public bool DisableNativeMenus { get; set; }
         
         public bool DisableSetProcessName { get; set; }
+        
+        /// <summary>
+        /// Gets or sets a value indicating whether Avalonia can install its own AppDelegate.
+        /// Disabling this can be useful in some scenarios like when running as a plugin inside an existing macOS application.
+        /// </summary>
+        public bool DisableAvaloniaAppDelegate { get; set; }
     }
 }

src/Avalonia.Native/avn.idl

@@ -600,6 +600,7 @@ interface IAvnMacOptions : IUnknown
      HRESULT SetShowInDock(int show);
      HRESULT SetApplicationTitle(char* utf8string);
      HRESULT SetDisableSetProcessName(int disable);
+     HRESULT SetDisableAppDelegate(int disable);
 }
 
 [uuid(04c1b049-1f43-418a-9159-cae627ec1367)]