public override void ModifyTags (MonoDevelop.Projects.SolutionItem policyParent, MonoDevelop.Projects.Project project, string language, string identifier, string fileName, ref Dictionary<string,string> tags)
		{
			base.ModifyTags (policyParent, project, language, identifier, fileName, ref tags);
			if (fileName == null)
				return;
			
			tags["AspNetMaster"] = "";
			tags["AspNetMasterContent"] = "";
			
			AspNetAppProject aspProj = project as AspNetAppProject;
			if (aspProj == null)
				throw new InvalidOperationException ("MasterContentFileDescriptionTemplate is only valid for ASP.NET projects");
			
			ProjectFile masterPage = null;
			string masterContent = "";
			
			var dialog = new MonoDevelop.Ide.Projects.ProjectFileSelectorDialog (aspProj, null, "*.master");
			try {
				dialog.Title = GettextCatalog.GetString ("Select a Master Page...");
				int response =  MonoDevelop.Ide.MessageService.RunCustomDialog (dialog);
				if (response == (int)Gtk.ResponseType.Ok)
					masterPage = dialog.SelectedFile;
			}
			finally {
				dialog.Destroy ();
			}
			if (masterPage == null)
				return;
			
			tags["AspNetMaster"] = aspProj.LocalToVirtualPath (masterPage);
			
			try {
				AspNetParsedDocument pd	= ProjectDomService.GetParsedDocument (ProjectDomService.GetProjectDom (project), masterPage.FilePath)
						as AspNetParsedDocument;
				if (pd == null)
					return;
				
				ContentPlaceHolderVisitor visitor = new ContentPlaceHolderVisitor ();
				pd.RootNode.AcceptVisit (visitor);
				
				System.Text.StringBuilder sb = new System.Text.StringBuilder ();
				foreach (string id in visitor.PlaceHolders) {
					sb.Append ("<asp:Content ContentPlaceHolderID=\"");
					sb.Append (id);
					sb.Append ("\" ID=\"");
					sb.Append (id);
					sb.Append ("Content\" runat=\"server\">\n</asp:Content>\n");
				}
				
				tags["AspNetMasterContent"] = sb.ToString ();
			}
			catch (Exception ex) {
				//no big loss if we just insert blank space
				//it's just a template for the user to start editing
			}
		}
		protected virtual void MasterChanged (object sender, EventArgs e)
		{
			if (IsPartialView || !HasMaster)
				return;
			
			if (masterEntry.Text == oldMaster)
				return;
			oldMaster = masterEntry.Text;
			
			primaryPlaceholderStore.Clear ();
			ContentPlaceHolders.Clear ();
			
			string realPath = project.VirtualToLocalPath (oldMaster, null);
			if (!File.Exists (realPath))
				return;
			
			var pd = ProjectDomService.GetParsedDocument (ProjectDomService.GetProjectDom (project), realPath)
				as AspNetParsedDocument;
			
			if (pd != null) {
				try {
					var visitor = new ContentPlaceHolderVisitor ();
					pd.RootNode.AcceptVisit (visitor);
					ContentPlaceHolders.AddRange (visitor.PlaceHolders);
					
					for (int i = 0; i < ContentPlaceHolders.Count; i++) {
						string placeholder = ContentPlaceHolders[i];
						primaryPlaceholderStore.AppendValues (placeholder);
						
						if (placeholder.Contains ("main") || placeholder.Contains ("Main") 
						    	|| placeholder.Contains ("content") || placeholder.Contains ("Main"))
							primaryPlaceholderCombo.Active = i;
					}
				} catch (Exception ex) {
					LoggingService.LogError ("Unhandled exception getting master regions for '" + realPath + "'", ex);
				}
			}
			
			Validate ();
		}