Simplify adding tabs

BuildTools/format.bat

@@ -1,3 +1,5 @@
 @rem This file can be used to trigger the commit hook's formatting,
 @rem modifying the local formatting even if not committing all changes.
+pushd %~dp0\..
 "%ProgramFiles%\Git\usr\bin\bash.exe" BuildTools\pre-commit --format
+popd

ILSpy/Docking/DockWorkspace.cs

@@ -88,6 +88,11 @@ namespace ICSharpCode.ILSpy.Docking
 		private void Documents_CollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
 		{
 			var collection = (PaneCollection<TabPageModel>)sender;
+			if (e.Action == NotifyCollectionChangedAction.Add)
+			{
+				ActiveTabPage = e.NewItems?[0] as TabPageModel;
+			}
+
 			bool canClose = collection.Count > 1;
 			foreach (var item in collection)
 			{

ILSpy/Docking/PaneCollection.cs

@@ -20,15 +20,13 @@ using System.Collections;
 using System.Collections.Generic;
 using System.Collections.ObjectModel;
 using System.Collections.Specialized;
-using System.ComponentModel;
-using System.Linq;
 
 using ICSharpCode.ILSpy.ViewModels;
 
 namespace ICSharpCode.ILSpy.Docking
 {
 	public class PaneCollection<T> : INotifyCollectionChanged, ICollection<T>
-		where T : PaneModel
+		where T : PaneModel, new()
 	{
 		private ObservableCollection<T> observableCollection = new ObservableCollection<T>();
 
@@ -39,8 +37,10 @@ namespace ICSharpCode.ILSpy.Docking
 			observableCollection.CollectionChanged += (sender, e) => CollectionChanged?.Invoke(this, e);
 		}
 
-		public void Add(T item)
+		public void Add(T item = null)
 		{
+			item ??= new T();
+
 			observableCollection.Add(item);
 
 			item.IsVisible = true;

ILSpy/MainWindow.xaml.cs

@@ -831,8 +831,7 @@ namespace ICSharpCode.ILSpy
 
 		void MainWindow_Loaded(object sender, RoutedEventArgs e)
 		{
-			DockWorkspace.Instance.TabPages.Add(new() { });
-			DockWorkspace.Instance.ActiveTabPage = DockWorkspace.Instance.TabPages.First();
+			DockWorkspace.Instance.TabPages.Add();
 
 			var loadPreviousAssemblies = Options.MiscSettingsPanel.CurrentMiscSettings.LoadPreviousAssemblies;
 
@@ -1087,8 +1086,7 @@ namespace ICSharpCode.ILSpy
 				{
 					if (inNewTabPage)
 					{
-						DockWorkspace.Instance.TabPages.Add(new TabPageModel() { });
-						DockWorkspace.Instance.ActiveTabPage = DockWorkspace.Instance.TabPages.Last();
+						DockWorkspace.Instance.TabPages.Add();
 						AssemblyTreeView.SelectedItem = null;
 					}
 
@@ -1130,8 +1128,7 @@ namespace ICSharpCode.ILSpy
 		{
 			if (inNewTabPage)
 			{
-				DockWorkspace.Instance.TabPages.Add(new TabPageModel() { });
-				DockWorkspace.Instance.ActiveTabPage = DockWorkspace.Instance.TabPages.Last();
+				DockWorkspace.Instance.TabPages.Add();
 			}
 
 			// Ensure nodes exist
@@ -1575,8 +1572,7 @@ namespace ICSharpCode.ILSpy
 			{
 				if (inNewTabPage)
 				{
-					DockWorkspace.Instance.TabPages.Add(new() { });
-					DockWorkspace.Instance.ActiveTabPage = DockWorkspace.Instance.TabPages.Last();
+					DockWorkspace.Instance.TabPages.Add();
 				}
 
 				if (e.Uri.Host == "aboutpage")