Make showing the navigation button on DocumentControl configurable

Author: eng-myousif

src/Eto/Forms/Controls/DocumentControl.cs

@@ -217,6 +217,17 @@ public bool AllowReordering
 		set { Handler.AllowReordering = value; }
 	}
 
+
+	/// <summary>
+	/// Gets or sets a value indicating the tabs can be navigated by next and previous buttons.
+	/// </summary>
+	/// <value><c>true</c> to allow navigating; otherwise, <c>false</c>.</value>
+	public bool AllowNavigating
+	{
+		get { return Handler.AllowNavigating; }
+		set { Handler.AllowNavigating = value; }
+	}
+
 		/// <summary>
 	/// Gets or sets the disabled foreground color.
 	/// </summary>
@@ -565,6 +576,12 @@ public void OnSelectedIndexChanged(DocumentControl widget, EventArgs e)
 		/// <value><c>true</c> to allow reordering; otherwise, <c>false</c>.</value>
 		bool AllowReordering { get; set; }
 
+		/// <summary>
+		/// Gets or sets a value indicating the tabs can be navigated by next and previous buttons.
+		/// </summary>
+		/// <value><c>true</c> to allow navigating; otherwise, <c>false</c>.</value>
+		bool AllowNavigating { get; set; }
+
 		/// <summary>
 		/// Gets or sets the disabled foreground color.
 		/// </summary>

src/Eto/Forms/ThemedControls/ThemedDocumentControlHandler.cs

@@ -8,6 +8,7 @@ public class ThemedDocumentControlHandler : ThemedContainerHandler<TableLayout,
 	List<DocumentPage> pages = new List<DocumentPage>();
 	ThemedDocumentPageHandler tabPrev, tabNext;
 
+	bool allowNavigating;
 	PointF mousePos;
 	int selectedIndex;
 	float nextPrevWidth;
@@ -42,6 +43,20 @@ public Padding TabPadding
 		set => Widget.Properties.Set(TabPadding_Key, value, DefaultTabPadding);
 	}
 
+	/// <summary>
+	/// Gets or sets a value indicating indicating the tabs can be navigated by next and previous buttons.
+	/// </summary>
+	/// <value><c>true</c> if navigatable; otherwise, <c>false</c>.</value>
+	public bool AllowNavigating
+	{
+		get { return allowNavigating; }
+		set
+		{
+			allowNavigating = value;
+			Calculate();
+		}
+	}
+
 	/// <summary>
 	/// Gets or sets the font for the tab text.
 	/// </summary>
@@ -189,6 +204,7 @@ public ThemedDocumentControlHandler()
 	{
 		mousePos = new PointF(-1, -1);
 		selectedIndex = -1;
+		allowNavigating = true;
 		nextPrevWidth = 0;
 		startx = 0;
 		font = SystemFonts.Default();
@@ -531,7 +547,7 @@ void CalculateTabs(bool force = false)
 		if (!force && !Widget.Loaded)
 			return;
 		var posx = 0f;
-		if (nextPrevWidth == 0f)
+		if (allowNavigating && nextPrevWidth == 0f)
 		{
 			CalculateTab(tabPrev, -1, ref posx);
 			CalculateTab(tabNext, -1, ref posx);
@@ -568,8 +584,11 @@ void Drawable_Paint(object sender, PaintEventArgs e)
 
 		posx = 0;
 
-		DrawTab(g, tabPrev, -1);
-		DrawTab(g, tabNext, -1);
+		if (allowNavigating)
+		{
+			DrawTab(g, tabPrev, -1);
+			DrawTab(g, tabNext, -1);
+		}
 	}
 
 	void CalculateTab(ThemedDocumentPageHandler tab, int i, ref float posx)