Merge pull request #2574 from eng-myousif/mo_youssef/enable_styling_d…

…ocument_control_tabs

Add capability for styling DocumentControl tabs

src/Eto.Gtk/Forms/Controls/DocumentControlHandler.cs

@@ -148,6 +148,12 @@ void SetShowTabs()
 
 		internal void ClosePage(Gtk.Widget control, DocumentPage page)
 		{
+			var args = new DocumentPageClosingEventArgs(page);
+			Callback.OnPageClosing(Widget, args);
+
+			if (args.Cancel)
+				return;
+
 			Control.RemovePage(Control.PageNum(control));
 			SetShowTabs();
 

src/Eto/Forms/Controls/DocumentControl.cs

@@ -21,6 +21,27 @@ public DocumentPageEventArgs(DocumentPage page)
 	}
 }
 
+/// <summary>
+/// Arguments for the <see cref="DocumentControl"/> to get the current page.
+/// </summary>
+public class DocumentPageClosingEventArgs : CancelEventArgs
+{
+	/// <summary>
+	/// Gets the document page.
+	/// </summary>
+	/// <value>The document page.</value>
+	public DocumentPage Page { get; private set; }
+
+	/// <summary>
+	/// Initializes a new instance of the <see cref="T:Eto.Forms.DocumentPageClosingEventArgs"/> class.
+	/// </summary>
+	/// <param name="page">Page.</param>
+	public DocumentPageClosingEventArgs(DocumentPage page)
+	{
+		Page = page;
+	}
+}
+
 /// <summary>
 /// Arguments for the <see cref="DocumentControl"/> when reordering pages.
 /// </summary>
@@ -70,6 +91,7 @@ public class DocumentControl : Container
 	public override IEnumerable<Control> Controls => pages ?? Enumerable.Empty<Control>();
 
 	static readonly object PageClosedEvent = new object();
+	static readonly object PageClosingEvent = new object();
 	static readonly object SelectedIndexChangedEvent = new object();
 
 	/// <summary>
@@ -86,6 +108,15 @@ public event EventHandler<DocumentPageEventArgs> PageClosed
 		remove { Properties.RemoveEvent(PageClosedEvent, value); }
 	}
 
+	/// <summary>
+	/// Occurs when the <see cref="DocumentPage"/> is closing.
+	/// </summary>
+	public event EventHandler<DocumentPageClosingEventArgs> PageClosing
+	{
+		add { Properties.AddEvent(PageClosingEvent, value); }
+		remove { Properties.RemoveEvent(PageClosingEvent, value); }
+	}
+
 	/// <summary>
 	/// Occurs when the <see cref="SelectedIndex"/> is changed.
 	/// </summary>
@@ -116,6 +147,15 @@ protected virtual void OnPageClosed(DocumentPageEventArgs e)
 			page.TriggerClose(e);
 	}
 
+	/// <summary>
+	/// Raises the <see cref="PageClosing"/> event.
+	/// </summary>
+	/// <param name="e">Event arguments.</param>
+	protected virtual void OnPageClosing(DocumentPageClosingEventArgs e)
+	{
+		Properties.TriggerEvent(PageClosingEvent, this, e);
+	}
+
 	/// <summary>
 	/// Raises the <see cref="SelectedIndexChanged"/> event.
 	/// </summary>
@@ -350,6 +390,11 @@ IEnumerator IEnumerable.GetEnumerator()
 		/// </summary>
 		void OnPageClosed(DocumentControl widget, DocumentPageEventArgs e);
 
+		/// <summary>
+		/// Raises the page closing event.
+		/// </summary>
+		void OnPageClosing(DocumentControl widget, DocumentPageClosingEventArgs e);
+
 		/// <summary>
 		/// Raises the selected index changed event.
 		/// </summary>
@@ -375,6 +420,15 @@ public void OnPageClosed(DocumentControl widget, DocumentPageEventArgs e)
 				widget.OnPageClosed(e);
 		}
 
+		/// <summary>
+		/// Raises the page closing event.
+		/// </summary>
+		public void OnPageClosing(DocumentControl widget, DocumentPageClosingEventArgs e)
+		{
+			using (widget.Platform.Context)
+				widget.OnPageClosing(e);
+		}
+
 		/// <summary>
 		/// Raises the page reordered event.
 		/// </summary>