private int total_dirs;
        private int searched_until_now_dirs;
        private int max_percentage;
        private TreeNode directories_real_time;
        private string SummaryText;

        private TreeNode CreateDirectoryNode(string path, string name , int recursive_levl )
        {
            var directoryNode = new TreeNode(name);
            var directoryListing = GetDirectoryListing(path);

            var directories = directoryListing.Where(d => d.IsDirectory);
            var files = directoryListing.Where(d => !d.IsDirectory);

            total_dirs += directories.Count<FTPListDetail>();
            searched_until_now_dirs++;

            int percentage;

            foreach (var dir in directories)
            {

                directoryNode.Nodes.Add(CreateDirectoryNode(dir.FullPath, dir.Name, recursive_levl+1));


                if (recursive_levl == 1)
                {
                    TreeNode temp_tn = (TreeNode)directoryNode.Clone();

                    this.BeginInvoke(new MethodInvoker( delegate
                    {
                        UpdateList(temp_tn);
                    }));
                }


                percentage = (searched_until_now_dirs * 100) / total_dirs;
                if (percentage > max_percentage)
                {
                    SummaryText = String.Format("Searched dirs {0} / Total dirs {1}", searched_until_now_dirs, total_dirs);
                    max_percentage = percentage;
                    backgroundWorker1.ReportProgress(percentage, SummaryText);
                }
            }

            percentage = (searched_until_now_dirs * 100) / total_dirs;
            if (percentage > max_percentage)
            {
                SummaryText = String.Format("Searched dirs {0} / Total dirs {1}", searched_until_now_dirs, total_dirs);
                max_percentage = percentage;
                backgroundWorker1.ReportProgress(percentage, SummaryText);
            }

            foreach (var file in files)
            {
                TreeNode file_tree_node = new TreeNode(file.Name);
                file_tree_node.Tag = "file";

                directoryNode.Nodes.Add(file_tree_node);
                numberOfFiles.Add(file.FullPath);
            }
            return directoryNode;
        }

private void menuStrip_ItemClicked(object sender, ToolStripItemClickedEventArgs e)
        {
            if (e.ClickedItem.Text == "Delete")
            {
                if (treeView1.SelectedNode.Tag != null)
                {
                    string s = (string)treeView1.SelectedNode.Tag; // this is casting
                    string s1 = treeView1.SelectedNode.Tag as string;
                    if (s == "file")
                    {
                        DeleteFile(treeView1.SelectedNode.FullPath);
                    }
                }
            }
        }