Also implementing the ScrollBarView in the ComboBox of the ListsAndCombos scenario.

Terminal.Gui/Views/ListView.cs

@@ -210,7 +210,7 @@ namespace Terminal.Gui {
 				if (source == null)
 					return;
 
-				if (top < 0 || (source.Count > 0 && top >= source.Count))
+				if (value < 0 || (source.Count > 0 && value >= source.Count))
 					throw new ArgumentException ("value");
 				top = value;
 				SetNeedsDisplay ();
@@ -227,7 +227,7 @@ namespace Terminal.Gui {
 				if (source == null)
 					return;
 
-				if (left < 0 || (Maxlength > 0 && left >= Maxlength))
+				if (value < 0 || (Maxlength > 0 && value >= Maxlength))
 					throw new ArgumentException ("value");
 				left = value;
 				SetNeedsDisplay ();

UICatalog/Scenarios/ListsAndCombos.cs

@@ -83,6 +83,33 @@ namespace UICatalog.Scenarios {
 			comboBox.SelectedItemChanged += (ListViewItemEventArgs text) => lbComboBox.Text = items[comboBox.SelectedItem];
 			Win.Add (lbComboBox, comboBox);
 
+			var scrollBarCbx = new ScrollBarView (comboBox.Subviews [1], true);
+
+			scrollBarCbx.ChangedPosition += () => {
+				((ListView)comboBox.Subviews [1]).TopItem = scrollBarCbx.Position;
+				if (((ListView)comboBox.Subviews [1]).TopItem != scrollBarCbx.Position) {
+					scrollBarCbx.Position = ((ListView)comboBox.Subviews [1]).TopItem;
+				}
+				comboBox.SetNeedsDisplay ();
+			};
+
+			scrollBarCbx.OtherScrollBarView.ChangedPosition += () => {
+				((ListView)comboBox.Subviews [1]).LeftItem = scrollBarCbx.OtherScrollBarView.Position;
+				if (((ListView)comboBox.Subviews [1]).LeftItem != scrollBarCbx.OtherScrollBarView.Position) {
+					scrollBarCbx.OtherScrollBarView.Position = ((ListView)comboBox.Subviews [1]).LeftItem;
+				}
+				comboBox.SetNeedsDisplay ();
+			};
+
+			comboBox.DrawContent += (e) => {
+				scrollBarCbx.Size = comboBox.Source.Count + 1;
+				scrollBarCbx.Position = ((ListView)comboBox.Subviews [1]).TopItem;
+				scrollBarCbx.OtherScrollBarView.Size = ((ListView)comboBox.Subviews [1]).Maxlength;
+				scrollBarCbx.OtherScrollBarView.Position = ((ListView)comboBox.Subviews [1]).LeftItem;
+				scrollBarCbx.Refresh ();
+			};
+
+
 			var btnMoveUp = new Button ("Move _Up") {
 				X = 1,
 				Y = Pos.Bottom(lbListView),