Hi, I would render all folders and files on the same page and then use a jQuery treeview plugin. Something like this:

public partial class FileList : UserControlBase
{
    const string DirectoryFormat = "<a class=\"folder\"><span>{0}</span></a>\r\n";
    const string FileFormat = "<li><a class=\"file {0}\" href=\"{1}\"><span>{2}</span> ({0}, {3})</a></li>\r\n";

    protected override void Render(HtmlTextWriter writer)
    {
        base.Render(writer);

        UnifiedDirectory root = CurrentPage.GetPageDirectory(true);

        if (root.QueryDistinctAccess(AccessLevel.Read))
        {
            writer.WriteLine("<ul class=\"file-list sitemap collapsable\">");
            writer.WriteLine("<li>");

            writer.Write(
                DirectoryFormat,
                HttpUtility.HtmlEncode(root.Name));

            ListDirectories(root, writer);

            writer.WriteLine("</li>");
            writer.WriteLine("</ul>");
        }
    }

    private void ListDirectories(UnifiedDirectory directory, HtmlTextWriter writer)
    {
        writer.WriteLine("<ul>");

        foreach (UnifiedDirectory subDirectory in directory.Directories)
        {
            if (subDirectory.QueryDistinctAccess(AccessLevel.Read))
            {
                writer.WriteLine("<li class=\"collapse\">");

                writer.Write(
                    DirectoryFormat,
                    HttpUtility.HtmlEncode(subDirectory.Name));

                ListDirectories(subDirectory, writer);

                writer.WriteLine("</li>");
            }
        }

        foreach (UnifiedFile file in directory.Files)
        {
            if (file.QueryDistinctAccess(AccessLevel.Read))
            {
                writer.Write(
                    FileFormat,
                    file.Extension.Remove(0, 1),
                    HttpUtility.UrlPathEncode(file.VirtualPath),
                    HttpUtility.HtmlEncode(file.Name),
                    file.Length.ToFileSize());
            }
        }

        writer.WriteLine("</ul>");
    }
}

Ah great! I shall give it a try... I'll get back once I run into problems :) Thanks...

I've managed to get the tree listing working okey but I'm having some problems with the URLs not leading to the files. Must have a closer look at my code and web.config. I shall also look into the jquery tree listing you mentioned... One thing I wonder though is how to skip showing/listing the top level (root directory - in my case 15375) first in the listing? Many thanks Johan!

Okey, now I've managed to get the whole thing working with JQuery Treeview and all (at home)... Great and many thanks for your advice! Files are linking correctly also. Must be some config or local enviroment thing thats wrong/weird at work. One thing that I ran into when importing the .js files (using ResolveUrl)... Everything compiled OK and worked as long as I was navigating but once I tried to login via util/login.aspx it kind of blew up in my face. I had to wrap the whole import in a contentplaceholder to avoid getting an error (when logging in). My question... Are there other (better) was of adding .js to the project?

<asp:ContentPlaceHolder id="fixing"runat="server">

<script src="<%= ResolveUrl("~/Templates/Scripts/Treeview/Lib/jquery.js") %>"type="text/javascript"></script>

<script src="<%= ResolveUrl("~/Templates/Scripts/Treeview/Lib/jquery.cookie.js") %>"type="text/javascript"></script>

<script src="<%= ResolveUrl("~/Templates/Scripts/Treeview/jquery.treeview.js") %>"type="text/javascript"></script>

<script src="<%= ResolveUrl("~/Templates/Scripts/Treeview/demo.js") %>"type="text/javascript"></script>

</asp:ContentPlaceHolder>