diff --git a/src/Avalonia.Native.OSX/window.mm b/src/Avalonia.Native.OSX/window.mm
index 2b04fd2e42..608f828e0e 100644
--- a/src/Avalonia.Native.OSX/window.mm
+++ b/src/Avalonia.Native.OSX/window.mm
@@ -44,6 +44,13 @@ public:
         return S_OK;
     }
     
+    virtual HRESULT SetTopMost (bool value)
+    {
+        [Window setLevel: value ? NSFloatingWindowLevel : NSNormalWindowLevel];
+        
+        return S_OK;
+    }
+    
     virtual HRESULT Close()
     {
         [Window close];
@@ -60,6 +67,19 @@ public:
         return S_OK;
     }
     
+    virtual HRESULT GetMaxClientSize(AvnSize* ret)
+    {
+        if(ret == nullptr)
+            return E_POINTER;
+        
+        auto size = [NSScreen.screens objectAtIndex:0].frame.size;
+        
+        ret->Height = size.height;
+        ret->Width = size.width;
+        
+        return S_OK;
+    }
+    
     virtual HRESULT GetScaling (double* ret)
     {
         if(ret == nullptr)
@@ -468,6 +488,11 @@ NSArray* AllLoopModes = [NSArray arrayWithObjects: NSDefaultRunLoopMode, NSEvent
     
     return (AvnInputModifiers)rv;
 }
+
+- (void)viewDidChangeBackingProperties
+{
+    _parent->BaseEvents->ScalingChanged();
+}
 @end
 
 
diff --git a/src/Avalonia.Native/Helpers.cs b/src/Avalonia.Native/Helpers.cs
index 941dd1dd14..77673edd1b 100644
--- a/src/Avalonia.Native/Helpers.cs
+++ b/src/Avalonia.Native/Helpers.cs
@@ -14,5 +14,10 @@ namespace Avalonia.Native
         {
             return new AvnPoint { X = pt.X, Y = pt.Y };
         }
+
+        public static Size ToAvaloniaSize (this AvnSize size)
+        {
+            return new Size(size.Width, size.Height);
+        }
     }
 }
diff --git a/src/Avalonia.Native/WindowImplBase.cs b/src/Avalonia.Native/WindowImplBase.cs
index f40d8ad4e7..98068773a8 100644
--- a/src/Avalonia.Native/WindowImplBase.cs
+++ b/src/Avalonia.Native/WindowImplBase.cs
@@ -129,7 +129,7 @@ namespace Avalonia.Native
                 _parent.Resized?.Invoke(s);
             }
 
-            public void RawMouseEvent(AvnRawMouseEventType type, uint timeStamp, AvnInputModifiers modifiers, AvnPoint point, AvnVector delta)
+            void IAvnWindowBaseEvents.RawMouseEvent(AvnRawMouseEventType type, uint timeStamp, AvnInputModifiers modifiers, AvnPoint point, AvnVector delta)
             {
                 _parent.RawMouseEvent(type, timeStamp, modifiers, point, delta);
             }
@@ -235,27 +235,32 @@ namespace Avalonia.Native
             _native.BeginMoveDrag();
         }
 
-        #region Stubs
+        public Size MaxClientSize => _native.GetMaxClientSize().ToAvaloniaSize();
+
+        public void SetTopmost(bool value)
+        {
+            _native.SetTopMost(value);
+        }
+
         public double Scaling => _native.GetScaling();
 
-        public Action<Point> PositionChanged { get; set; }
         public Action Deactivated { get; set; }
         public Action Activated { get; set; }
+
+        #region Stubs
+
+        public Action<Point> PositionChanged { get; set; }
+
         public Action<RawInputEventArgs> Input { get; set; }
 
         Action<double> ScalingChanged { get; set; }
         public IPlatformHandle Handle => new PlatformHandle(IntPtr.Zero, "NOT SUPPORTED");
 
-        public Size MaxClientSize => new Size(1600, 900);
 
         public IScreenImpl Screen => new ScreenImpl();
 
         Action<double> ITopLevelImpl.ScalingChanged { get; set; }
 
-        public void SetTopmost(bool value)
-        {
-        }
-
         public void SetMinMaxSize(Size minSize, Size maxSize)
         {
         }
diff --git a/src/headers/avalonia-native.h b/src/headers/avalonia-native.h
index d5d13a369d..8d637e7f38 100644
--- a/src/headers/avalonia-native.h
+++ b/src/headers/avalonia-native.h
@@ -90,6 +90,7 @@ AVNCOM(IAvnWindowBase, 02) : virtual IUnknown
     virtual HRESULT Hide () = 0;
     virtual HRESULT Close() = 0;
     virtual HRESULT GetClientSize(AvnSize*ret) = 0;
+    virtual HRESULT GetMaxClientSize(AvnSize* ret) = 0;
     virtual HRESULT GetScaling(double*ret)=0;
     virtual HRESULT Resize(double width, double height) = 0;
     virtual void Invalidate (AvnRect rect) = 0;
@@ -99,6 +100,7 @@ AVNCOM(IAvnWindowBase, 02) : virtual IUnknown
     virtual HRESULT PointToClient (AvnPoint point, AvnPoint*ret) = 0;
     virtual HRESULT PointToScreen (AvnPoint point, AvnPoint*ret) = 0;
     virtual HRESULT ThreadSafeSetSwRenderedFrame(AvnFramebuffer* fb, IUnknown* dispose) = 0;
+    virtual HRESULT SetTopMost (bool value) = 0;
 };
 
 AVNCOM(IAvnPopup, 03) : virtual IAvnWindowBase