Window OnLoadComplete and GetPreferredSize improvements

- OnLoadComplete is now called by Window handler implementations at the appropriate time
- Window.GetPrerredSize() should now be guaranteed to work for a Window during the LoadComplete event on all platforms, and for some platforms before it is shown.
- Gtk still has issues including the window decorations with the preferred size, work is ongoing there.
- Mac now calls Window.Shown after children get the same event, like other platforms.

src/Eto.Gtk/Forms/DialogHandler.cs

@@ -18,6 +18,7 @@ public DialogHandler()
 		protected override void Initialize()
 		{
 			base.Initialize();
+			Control.Modal = true;
 			Control.KeyPressEvent += Connector.Control_KeyPressEvent;
 
 			var vbox = new EtoBox(Gtk.Orientation.Vertical, 0) { Handler = this };
@@ -96,14 +97,24 @@ public void ShowModal()
 			DisableAutoSizeUpdate++;
 			ReloadButtons();
 
-			Control.Modal = true;
+			Control.Child?.ShowAll();
+			if (!Control.IsRealized)
+			{
+				Control.Realize();
+			}
+			Control.QueueResize();
+			Callback.OnLoadComplete(Widget, EventArgs.Empty);
+
 			Control.ShowAll();
 			DisableAutoSizeUpdate--;
 
-			do
+			if (!WasClosed)
 			{
-				Control.Run();
-			} while (!WasClosed && !CloseWindow());
+				do
+				{
+					Control.Run();
+				} while (!WasClosed && !CloseWindow());
+			}
 
 			WasClosed = false;
 			Control.Hide();
@@ -185,20 +196,13 @@ public void RemoveDialogButton(bool positive, int index, Button item)
 			}
 		}
 
-		static readonly object WasClosedKey = new object();
-
-		bool WasClosed
-		{
-			get { return Widget.Properties.Get<bool>(WasClosedKey); }
-			set { Widget.Properties.Set(WasClosedKey, value); }
-		}
-
 		public override void Close()
 		{
-			if (CloseWindow())
+			if (Widget.Loaded && CloseWindow())
 			{
-				WasClosed = true;
 				Control.Hide();
+				Control.Unrealize();
+				WasClosed = true;
 			}
 		}
 

src/Eto.Gtk/Forms/FormHandler.cs

@@ -26,6 +26,8 @@ public async void Show()
 		{
 			DisableAutoSizeUpdate++;
 			Control.Child.ShowAll();
+			Control.Realize();
+			Callback.OnLoadComplete(Widget, EventArgs.Empty);
 			if (ShowActivated || !Control.AcceptFocus)
 				Control.Show();
 			else

src/Eto.Gtk/Forms/GtkControl.cs

@@ -21,6 +21,8 @@ public interface IGtkControl
 
 		void TriggerMouseEnterIfNeeded();
 		void TriggerMouseLeaveIfNeeded();
+
+		Control.ICallback Callback { get; }
 	}
 
 	public static class GtkControlExtensions
@@ -1150,8 +1152,12 @@ public virtual SizeF GetPreferredSize(SizeF availableSize)
 		{
 			if (!ContainerControl.IsRealized)
 			{
+				if (ContainerControl is Gtk.Window window)
+					window.Child.ShowAll();
+				else
+					ContainerControl.ShowAll();
+
 				ContainerControl.Realize();
-				ContainerControl.ShowAll();
 			}
 #if GTK3
 			var requestMode = ContainerControl.RequestMode;
@@ -1236,6 +1242,8 @@ public bool IsMouseCaptured
 
 		Control IGtkControl.Widget => Widget;
 
+		Control.ICallback IGtkControl.Callback => Callback;
+
 		public void TriggerMouseEnterIfNeeded() => Connector.TriggerMouseEnterIfNeeded();
 		public void TriggerMouseLeaveIfNeeded() => Connector.TriggerMouseLeaveIfNeeded();
 

src/Eto.Gtk/Forms/GtkWindow.cs

@@ -11,6 +11,8 @@ public interface IGtkWindow
 		Gtk.Window Control { get; }
 
 		Size UserPreferredSize { get; }
+
+		Window.ICallback Callback { get; }
 	}
 
 	public class GtkShrinkableVBox : Gtk.Box
@@ -188,7 +190,7 @@ private void SetMinMax(Size? size)
 #endif
 			Control.SetGeometryHints(Control, geom, Gdk.WindowHints.MinSize);
 		}
-		
+
 
 		public bool Minimizable
 		{
@@ -215,7 +217,7 @@ public bool ShowInTaskbar
 			get { return !Control.SkipTaskbarHint; }
 			set { Control.SkipTaskbarHint = !value; }
 		}
-		
+
 		public bool Closeable
 		{
 			get => Control.Deletable;
@@ -262,9 +264,9 @@ public WindowStyle WindowStyle
 				}
 			}
 		}
-		
+
 		protected virtual Gdk.WindowTypeHint DefaultTypeHint => Gdk.WindowTypeHint.Normal;
-		
+
 		void SetTypeHint()
 		{
 			if (WindowStyle == WindowStyle.Default && (Minimizable || Maximizable))
@@ -284,7 +286,7 @@ public override Size Size
 			{
 				DisableAutoSizeUpdate++;
 				UserPreferredSize = value;
-					
+
 				if (Widget.Loaded)
 				{
 					var diff = WindowDecorationSize;
@@ -447,7 +449,10 @@ public void HandleDeleteEvent(object o, Gtk.DeleteEventArgs args)
 
 			public void HandleShownEvent(object sender, EventArgs e)
 			{
-				Handler?.Callback.OnShown(Handler.Widget, EventArgs.Empty);
+				var h = Handler;
+				if (h == null || h.WasClosed)
+					return;
+				Application.Instance.AsyncInvoke(() => h.Callback.OnShown(Handler.Widget, EventArgs.Empty));
 			}
 
 			public void HandleWindowStateEvent(object o, Gtk.WindowStateEventArgs args)
@@ -615,12 +620,22 @@ public bool CloseWindow(Action<CancelEventArgs> closing = null)
 			return !args.Cancel;
 		}
 
+		static readonly object WasClosedKey = new object();
+
+		protected bool WasClosed
+		{
+			get { return Widget.Properties.Get<bool>(WasClosedKey); }
+			set { Widget.Properties.Set(WasClosedKey, value); }
+		}
+
+
 		public virtual void Close()
 		{
 			if (Widget.Loaded && CloseWindow())
 			{
 				Control.Hide();
 				Control.Unrealize();
+				WasClosed = true;
 			}
 		}
 
@@ -797,7 +812,7 @@ public void BringToFront()
 				if (WindowState == WindowState.Minimized)
 					Control.Present();
 			}
-			
+
 			Control.GetWindow()?.Raise();
 		}
 
@@ -868,13 +883,21 @@ Size WindowDecorationSize
 		{
 			get
 			{
+				if (!Control.IsRealized)
+				{
+					Control.Child?.ShowAll();
+					Control.Realize();
+				}
+
 				var window = Control.GetWindow();
 				if (window == null)
 					return Size.Empty;
 				return window.FrameExtents.Size.ToEto() - Control.Allocation.Size.ToEto();
 			}
 		}
 
+		Window.ICallback IGtkWindow.Callback => Callback;
+
 		bool isInvalidated;
 
 		internal void PerformResize()

src/Eto.Mac/Forms/DialogHandler.cs

@@ -143,6 +143,8 @@ bool ShowAttached
 
 		public virtual void ShowModal()
 		{
+			Control.LayoutIfNeeded();
+			Callback.OnLoadComplete(Widget, EventArgs.Empty);
 			MacView.InMouseTrackingLoop = false;
 			session = null;
 			EnsureOwner();
@@ -160,6 +162,8 @@ public virtual void ShowModal()
 
 		public virtual Task ShowModalAsync()
 		{
+			Control.LayoutIfNeeded();
+			Callback.OnLoadComplete(Widget, EventArgs.Empty);
 			MacView.InMouseTrackingLoop = false;
 			var tcs = new TaskCompletionSource<bool>();
 			session = null;

src/Eto.Mac/Forms/FormHandler.cs

@@ -58,6 +58,8 @@ protected override void Initialize()
 
 		public virtual void Show()
 		{
+			Control.LayoutIfNeeded();
+			Callback.OnLoadComplete(Widget, EventArgs.Empty);
 			var visible = Control.IsVisible;
 			if (ShowActivated)
 			{

src/Eto.Mac/Forms/MacView.cs

@@ -1343,12 +1343,20 @@ static void FireOnShown(Control control)
 			// don't use GetMacViewHandler() extension, as that will trigger OnShown for themed controls, which will
 			// trigger Shown multiple times for the same themed control
 			var handler = control.Handler as IMacViewHandler;
-			handler?.Callback.OnShown(control, EventArgs.Empty);
+			var isWindow = control is Window;
+
+			// Parent controls get shown event first, then children
+			if (!isWindow)
+				handler?.Callback.OnShown(control, EventArgs.Empty);
 
 			foreach (var ctl in control.VisualControls)
 			{
 				FireOnShown(ctl);
 			}
+
+			// Window fires shown after all child controls
+			if (isWindow)
+				handler?.Callback.OnShown(control, EventArgs.Empty);
 		}
 
 		protected virtual void FireOnShown() => FireOnShown(Widget);

src/Eto.Mac/Forms/MacWindow.cs

@@ -281,7 +281,9 @@ protected override SizeF GetNaturalSize(SizeF availableSize)
 					naturalSize.Height = preferredClientSize.Value.Height;
 			}
 
-			return naturalSize;
+			var frame = Control.FrameRectFor(new RectangleF(naturalSize).ToNS());
+
+			return frame.Size.ToEto();
 		}
 
 		public NSMenu MenuBar
@@ -788,7 +790,7 @@ private void PerformAutoSize()
 				if (UserPreferredSize.Height != -1)
 					availableSize.Height = UserPreferredSize.Height - borderSize.Height;
 				var size = GetPreferredSize(availableSize);
-				SetContentSize(size.ToNS());
+				SetSize(size.ToNS());
 			}
 		}
 
@@ -1170,33 +1172,17 @@ protected virtual void PositionWindow()
 
 		#region IMacContainer implementation
 
-		void SetContentSize(CGSize contentSize)
+		void SetSize(CGSize newSize)
 		{
 			if (MinimumSize != Size.Empty)
 			{
-				contentSize.Width = (nfloat)Math.Max(contentSize.Width, MinimumSize.Width);
-				contentSize.Height = (nfloat)Math.Max(contentSize.Height, MinimumSize.Height);
+				newSize.Width = (nfloat)Math.Max(newSize.Width, MinimumSize.Width);
+				newSize.Height = (nfloat)Math.Max(newSize.Height, MinimumSize.Height);
 			}
 
-			if (Widget.Loaded)
-			{
-				var clientSize = ClientSize;
-				var diffy = clientSize.Height - (int)contentSize.Height;
-				var diffx = clientSize.Width - (int)contentSize.Width;
-				var frame = Control.Frame;
-				if (diffx != 0 || setInitialSize)
-				{
-					frame.Width -= diffx;
-				}
-				if (diffy != 0 || setInitialSize)
-				{
-					frame.Y += diffy;
-					frame.Height -= diffy;
-				}
-				Control.SetFrame(frame, true, AnimateSizeChanges);
-			}
-			else
-				Control.SetContentSize(contentSize);
+			var frame = Control.Frame;
+			frame.Size = newSize;
+			Control.SetFrame(frame, Widget.Loaded, AnimateSizeChanges);
 		}
 
 		#endregion

src/Eto.WinForms/Forms/WindowHandler.cs

@@ -194,6 +194,8 @@ void Control_Load(object sender, EventArgs e)
 			Control.Size = size;
 			content.MinimumSize = content.MaximumSize = sd.Size.Empty;
 			ContainerContentControl.MinimumSize = sd.Size.Empty;
+
+			Callback.OnLoadComplete(Widget, EventArgs.Empty);
 		}
 
 		public override Size Size

src/Eto.Wpf/Forms/DialogHandler.cs

@@ -102,6 +102,18 @@ public void ShowModal()
 			if (owner != null && !owner.HasFocus)
 				owner.Focus();
 
+			if (Control.IsLoaded)
+			{
+				Callback.OnLoadComplete(Widget, EventArgs.Empty);
+				FireOnLoadComplete = false;
+			}
+			else
+			{
+				FireOnLoadComplete = true;
+			}
+
+			var _ = NativeHandle; // ensure SourceInitialized is called to get right size based on style flags
+
 			Control.ShowDialog();
 			WpfFrameworkElementHelper.ShouldCaptureMouse = false;
 

src/Eto.Wpf/Forms/FormHandler.cs

@@ -40,10 +40,21 @@ public FormHandler()
 		public virtual void Show()
 		{
 			Control.WindowStartupLocation = sw.WindowStartupLocation.Manual;
-			if (ApplicationHandler.Instance.IsStarted)
+			if (Control.IsLoaded)
 			{
-				Control.Show();
+				Callback.OnLoadComplete(Widget, EventArgs.Empty);
+				FireOnLoadComplete = false;
 			}
+			else
+			{
+				// We should trigger during the Control.Loaded event
+				FireOnLoadComplete = true;
+			}
+
+			var _ = NativeHandle; // ensure SourceInitialized is called to get right size based on style flags
+
+			if (ApplicationHandler.Instance.IsStarted)
+				Control.Show();
 			else
 				ApplicationHandler.Instance.DelayShownWindows.Add(Control);
 			WpfFrameworkElementHelper.ShouldCaptureMouse = false;