Add incomplete OK implementation which *mostly* works. Fixed description invalid name.

src/Main/Base/Project/Src/Gui/Dialogs/NewFileViewModel.cs

@@ -111,13 +111,15 @@ namespace ICSharpCode.SharpDevelop.Gui
             set { _searchFor = value; }
         }
 
+        public string FileName { get; set; }
+
         public string Description
         {
             get
             {
                 return SelectedItem == null
                     ? string.Empty
-                    : SelectedItem.Template.Description;
+                    : SelectedItem.Description;
 
             }
             set { }

src/Main/Base/Project/Src/Gui/Dialogs/NewFileWindow.xaml

@@ -78,7 +78,7 @@
         			<ColumnDefinition />
         		</Grid.ColumnDefinitions>
         		<TextBlock Text="File name: " VerticalAlignment="Center" />
-	            <TextBox Grid.Column="1" Text="{Binding ItemFileName}" x:Name="fileNameTextBox" />
+	            <TextBox Grid.Column="1" Text="{Binding FileName}" x:Name="fileNameTextBox" />
 	        </Grid>
         	<widgets:UniformGridWithSpacing Columns="2" HorizontalAlignment="Right" Margin="0,4,12,12">
                 <Button

src/Main/Base/Project/Src/Gui/Dialogs/NewFileWindow.xaml.cs

@@ -9,7 +9,9 @@
 using System;
 using System.Collections.Generic;
 using System.Collections.ObjectModel;
+using System.IO;
 using System.Linq;
+using System.Text;
 using System.Windows;
 using System.Windows.Controls;
 using ICSharpCode.Core;
@@ -90,7 +92,29 @@ namespace ICSharpCode.SharpDevelop.Gui
             return node;
         }
 	    private void okButtonClick(object sender, RoutedEventArgs e)
-	    {
+        {
+
+            var selectedTemplate = ViewModel.SelectedItem;
+            var fileName = ViewModel.FileName;
+
+            var standardNamespace = "DefaultNamespace";
+
+            var localizedTypeDescriptor = selectedTemplate.Template.CreateCustomizationObject();
+            var options = new FileTemplateOptions
+            {
+                ClassName =
+                    GenerateValidClassOrNamespaceName(Path.GetFileNameWithoutExtension(ViewModel.FileName), false),
+                FileName = FileName.Create(fileName),
+                IsUntitled = ViewModel.AllowUntitledFiles,
+                Namespace = standardNamespace,
+                CustomizationObject = localizedTypeDescriptor,
+                Project = ViewModel.Project
+            };
+
+	        var result = selectedTemplate.Template.Create(options);
+            DialogResult = true;
+            if (result != null)
+                selectedTemplate.Template.RunActions(result);
             Close();
 	    }
 
@@ -98,6 +122,29 @@ namespace ICSharpCode.SharpDevelop.Gui
 	    {
             Close();
 	    }
+	    
+	    internal static string GenerateValidClassOrNamespaceName(string className, bool allowDot)
+		{
+			if (className == null)
+				throw new ArgumentNullException("className");
+			className = className.Trim();
+			if (className.Length == 0)
+				return string.Empty;
+			StringBuilder nameBuilder = new StringBuilder();
+			if (className[0] != '_' && !char.IsLetter(className, 0))
+				nameBuilder.Append('_');
+			for (int idx = 0; idx < className.Length; ++idx) {
+				if (Char.IsLetterOrDigit(className[idx]) || className[idx] == '_') {
+					nameBuilder.Append(className[idx]);
+				} else if (className[idx] == '.' && allowDot) {
+					nameBuilder.Append('.');
+				} else {
+					nameBuilder.Append('_');
+				}
+            }
+            return nameBuilder.ToString();
+        }
+			
 		void CategoryTreeView_SelectedItemChanged(object sender, RoutedPropertyChangedEventArgs<object> e)
 		{
 			ViewModel.SelectedCategory = (NewFileCategory)categoryTreeView.SelectedItem;