ComboBox. Adhere to ListView interface, added:-

SelectedItem (read only) from @BDisp
OpenSelectedItem

Example/demo.cs

@@ -449,7 +449,8 @@ static class Demo {
 
 	static void ComboBoxDemo ()
 	{
-		List<ustring> items = new List<ustring> ();
+		//TODO: Duplicated code in ListsAndCombos.cs Consider moving to shared assembly
+		var items = new List<ustring> ();
 		foreach (var dir in new [] { "/etc", @$"{Environment.GetEnvironmentVariable ("SystemRoot")}\System32" }) {
 			if (Directory.Exists (dir)) {
 				items = Directory.GetFiles (dir).Union (Directory.GetDirectories (dir))
@@ -459,8 +460,8 @@ static class Demo {
 			}
 		}
 		var list = new ComboBox () { Width = Dim.Fill(), Height = Dim.Fill() };
-		list.SetSource(items.ToList());
-		list.SelectedItemChanged += (object sender, ListViewItemEventArgs text) => { Application.RequestStop (); };
+		list.SetSource(items);
+		list.OpenSelectedItem += (ListViewItemEventArgs text) => { Application.RequestStop (); };
 
 		var d = new Dialog () { Title = "Select source file", Width = Dim.Percent (50), Height = Dim.Percent (50) };
 		d.Add (list);

Terminal.Gui/Views/ComboBox.cs

@@ -55,13 +55,14 @@ namespace Terminal.Gui {
 		}
 
 		/// <summary>
-		///   Changed event, raised when the selection has been confirmed.
+		/// This event is raised when the selected item in the <see cref="ComboBox"/> has changed.
 		/// </summary>
-		/// <remarks>
-		///   Client code can hook up to this event, it is
-		///   raised when the selection has been confirmed.
-		/// </remarks>
-		public event EventHandler<ListViewItemEventArgs> SelectedItemChanged;
+		public Action<ListViewItemEventArgs> SelectedItemChanged;
+
+		/// <summary>
+		/// This event is raised when the user Double Clicks on an item or presses ENTER to open the selected item.
+		/// </summary>
+		public Action<ListViewItemEventArgs> OpenSelectedItem;
 
 		IList searchset;
 		ustring text = "";
@@ -153,6 +154,12 @@ namespace Terminal.Gui {
 			};
 		}
 
+		/// <summary>
+		/// Gets the index of the currently selected item in the <see cref="Source"/>
+		/// </summary>
+		/// <value>The selected item or -1 none selected.</value>
+		public int SelectedItem { private set; get; }
+
 		bool isShow = false;
 
 		///<inheritdoc/>
@@ -209,7 +216,19 @@ namespace Terminal.Gui {
 		{
 			// Note: Cannot rely on "listview.SelectedItem != lastSelectedItem" because the list is dynamic. 
 			// So we cannot optimize. Ie: Don't call if not changed
-			SelectedItemChanged?.Invoke (this, new ListViewItemEventArgs(listview.SelectedItem, search.Text));
+			SelectedItemChanged?.Invoke (new ListViewItemEventArgs(SelectedItem, search.Text));
+
+			return true;
+		}
+
+		/// <summary>
+		/// Invokes the OnOpenSelectedItem event if it is defined.
+		/// </summary>
+		/// <returns></returns>
+		public virtual bool OnOpenSelectedItem ()
+		{
+			var value = search.Text;
+			OpenSelectedItem?.Invoke (new ListViewItemEventArgs (SelectedItem, value));
 
 			return true;
 		}
@@ -301,6 +320,8 @@ namespace Terminal.Gui {
 			this.text = search.Text = text.ToString();
 			search.CursorPosition = 0;
 			search.TextChanged += Search_Changed;
+			SelectedItem = GetSelectedItemFromSource (this.text);
+			OnSelectedChanged ();
 		}
 
 		private void Selected ()
@@ -313,10 +334,23 @@ namespace Terminal.Gui {
 			SetValue (searchset [listview.SelectedItem]);
 			search.CursorPosition = search.Text.RuneCount;
 			Search_Changed (search.Text);
-			OnSelectedChanged ();
+			OnOpenSelectedItem ();
 			Reset (keepSearchText: true);
 		}
 
+		private int GetSelectedItemFromSource (ustring value)
+		{
+			if (source == null) {
+				return -1;
+			}
+			for (int i = 0; i < source.Count; i++) {
+				if (source.ToList () [i].ToString () == value) {
+					return i;
+				}
+			}
+			return -1;
+		}
+
 		/// <summary>
 		/// Reset to full original list
 		/// </summary>

UICatalog/Scenarios/ListsAndCombos.cs

@@ -12,7 +12,8 @@ namespace UICatalog.Scenarios {
 
 		public override void Setup ()
 		{
-			List<ustring> items = new List<ustring> ();
+			//TODO: Duplicated code in Demo.cs Consider moving to shared assembly
+			var items = new List<ustring> ();
 			foreach (var dir in new [] { "/etc", @$"{Environment.GetEnvironmentVariable ("SystemRoot")}\System32" }) {
 				if (Directory.Exists (dir)) {
 					items = Directory.GetFiles (dir).Union(Directory.GetDirectories(dir))
@@ -35,7 +36,7 @@ namespace UICatalog.Scenarios {
 				Height = Dim.Fill(2),
 				Width = Dim.Percent (40)
 			};
-			listview.OpenSelectedItem += (ListViewItemEventArgs e) => lbListView.Text = items [listview.SelectedItem];
+			listview.SelectedItemChanged += (ListViewItemEventArgs e) => lbListView.Text = items [listview.SelectedItem];
 			Win.Add (lbListView, listview);
 
 			// ComboBox
@@ -53,7 +54,7 @@ namespace UICatalog.Scenarios {
 			};
 			comboBox.SetSource (items);
 
-			comboBox.SelectedItemChanged += (object sender, ListViewItemEventArgs text) => lbComboBox.Text = (ustring)text.Value;
+			comboBox.SelectedItemChanged += (ListViewItemEventArgs text) => lbComboBox.Text = items[comboBox.SelectedItem];
 			Win.Add (lbComboBox, comboBox);
 		}
 	}