Add explicit application activation on macOS

src/Eto.Mac/Forms/ApplicationHandler.cs

@@ -3,7 +3,7 @@
 using System.Runtime.CompilerServices;
 namespace Eto.Mac.Forms
 {
-	public class ApplicationHandler : MacObject<NSApplication, Application, Application.ICallback>, Application.IHandler
+	public class ApplicationHandler : MacObject<NSApplication, Application, Application.ICallback>, Application.IHandler, Application.IActivateHandler
 	{
 		bool _attached;
 		bool? _activateOnStartup;
@@ -371,15 +371,21 @@ internal void EnsureActivated(bool showInTaskbar, bool showActivated, Icon icon)
 			if (!showActivated)
 				return;
 
-			// taking activation from whatever app has it is only for callers that opted in, and has to be done
-			// for every window since another app can take it back at any point during a run
-			if (ActivateIgnoringOtherApps)
-				Control.ActivateIgnoringOtherApps(true);
-			// otherwise only ask for it as the app gets its first window, which is all macOS will grant anyway
-			else if (showInTaskbar && wasProhibited)
+			// Later shows should not take activation unless explicitly opted in.
+			if (ActivateIgnoringOtherApps || showInTaskbar && wasProhibited)
+				RequestActivation(false);
+		}
+
+		void RequestActivation(bool explicitlyRequested)
+		{
+			if (MacVersion.IsAtLeast(14, 0) && !ActivateIgnoringOtherApps)
 				Control.Activate();
+			else
+				Control.ActivateIgnoringOtherApps(explicitlyRequested || ActivateIgnoringOtherApps);
 		}
 
+		public void Activate() => RequestActivation(true);
+
 		public Keys CommonModifier => Keys.Application;
 
 		public Keys AlternateModifier => Keys.Alt;

src/Eto/Forms/Application.cs

@@ -583,6 +583,23 @@ public string BadgeLabel
 	/// <seealso cref="IsActiveChanged"/>
 	public bool IsActive => Handler.IsActive;
 
+	/// <summary>
+	/// Requests native application activation.
+	/// </summary>
+	/// <remarks>
+	/// This method is supported by the native macOS backend and has no effect on other backends.
+	/// The operating system may delay or decline activation; use <see cref="IsActive"/> and
+	/// <see cref="IsActiveChanged"/> to observe the activation state.
+	/// Call this method on the UI thread before calling <see cref="Control.Focus"/> on the desired window.
+	/// </remarks>
+	/// <seealso cref="IsActive"/>
+	/// <seealso cref="IsActiveChanged"/>
+	public void Activate()
+	{
+		EnsureUIThread();
+		(Handler as IActivateHandler)?.Activate();
+	}
+
 	/// <summary>
 	/// Advanced. Runs an iteration of the main UI loop when you are blocking the UI thread with logic.
 	/// </summary>
@@ -830,4 +847,15 @@ public void OnThemeChanged(Application widget, EventArgs e)
 		/// </summary>
 		Theme Theme { get; set; }
 	}
+
+	/// <summary>
+	/// Optional handler for native application activation.
+	/// </summary>
+	public interface IActivateHandler
+	{
+		/// <summary>
+		/// Requests native application activation.
+		/// </summary>
+		void Activate();
+	}
 }