Add OSX implementation.

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

@@ -106,13 +106,13 @@ public:
         return Window;
     }
     
-    virtual HRESULT Show() override
+    virtual HRESULT Show(bool activate) override
     {
         @autoreleasepool
         {
             SetPosition(lastPositionSet);
             UpdateStyle();
-            if(ShouldTakeFocusOnShow())
+            if(ShouldTakeFocusOnShow() && activate)
             {
                 [Window makeKeyAndOrderFront:Window];
                 [NSApp activateIgnoringOtherApps:YES];
@@ -561,11 +561,11 @@ private:
         }
     }
     
-    virtual HRESULT Show () override
+    virtual HRESULT Show (bool activate) override
     {
         @autoreleasepool
         {            
-            WindowBaseImpl::Show();
+            WindowBaseImpl::Show(activate);
             
             HideOrShowTrafficLights();
             

src/Avalonia.Native/PopupImpl.cs

@@ -60,14 +60,14 @@ namespace Avalonia.Native
             }
         }
 
-        public override void Show()
+        public override void Show(bool activate)
         {
             var parent = _parent;
             while (parent is PopupImpl p) 
                 parent = p._parent;
             if (parent is WindowImpl w)
                 w.Native.TakeFocusFromChildren();
-            base.Show();
+            base.Show(false);
         }
 
         public override IPopupImpl CreatePopup() => new PopupImpl(_factory, _opts, _glFeature, this);

src/Avalonia.Native/WindowImplBase.cs

@@ -351,9 +351,9 @@ namespace Avalonia.Native
         }
 
 
-        public virtual void Show()
+        public virtual void Show(bool activate)
         {
-            _native.Show();
+            _native.Show(activate.AsComBool());
         }
 
 

src/Avalonia.Native/avn.idl

@@ -225,7 +225,7 @@ interface IAvnString : IUnknown
 [uuid(e5aca675-02b7-4129-aa79-d6e417210bda)]
 interface IAvnWindowBase : IUnknown
 {
-     HRESULT Show();
+     HRESULT Show(bool activate);
      HRESULT Hide();
      HRESULT Close();
      HRESULT Activate();