Multithreaded File/Folder Finder

using System;
using System.Collections;
using System.Drawing;
using System.IO;
using System.Text;
using System.Windows.Forms;

namespace FileFind
{
    /// <summary>
    /// Displays a list of all available disk drives and allows selection of one or more disks.
    /// Disks listed in the configuration ignoreFolders array are marked as not selected
    /// </summary>
    public partial class DiskSelection : Form
    {
        private ArrayList selected;
        private ArrayList ignoreFolders;    //local copy

        private Point location = new Point();
        private bool locationSet = false;
        public Point FormLocation
        {
            get { return location; }
            set
            {
                location = value;
                locationSet = true;
            }
        }

        public DiskSelection(ArrayList select)
        {
            selected = select;
            InitializeComponent();
        }

        /// <summary>
        /// Build a list of disk drives, high lighting the selected drives
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void DiskSelection_Load(object sender, EventArgs e)
        {
            if (locationSet)
                this.Location = location;
            ConfigInfo configInfo = new ConfigInfo();
            this.Font = configInfo.UseFont;
            this.Text = configInfo.ProductName + " - " + this.Text;
            ignoreFolders = configInfo.IgnoreFolders;

            DriveInfo[] allDrives = null;
            try { allDrives = DriveInfo.GetDrives(); }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, configInfo.ProductName + " DiskSelection_Load",
                                MessageBoxButtons.OK, MessageBoxIcon.Asterisk);
                allDrives = null;
            }
            int readyDrives = 0;
            selectListBox.BeginUpdate();
            foreach (DriveInfo drive in allDrives)
            {   //show drives available
                if (drive.IsReady)
                {
                    ++readyDrives;
                    string driveDisplay = drive.Name + drive.VolumeLabel;
                    if (DriveType.Network == drive.DriveType)
                        driveDisplay += " (Network)";
                    int i = selectListBox.Items.Add(driveDisplay);
                    foreach (string dl in selected)
                        if (dl[0] == drive.Name[0])
                        {   //drive was preselected
                            if (FoundInIgnoreDirectory(drive.Name))
                                selectListBox.SetSelected(i, false);
                            else
                                selectListBox.SetSelected(i, true);
                            break;
                        }
                }
            }
            selectListBox.EndUpdate();
            if (selected.Count == readyDrives)
                selectAllDisks.Checked = false; //all drives have been selected
        } //ends private void DiskSelection_Load(...

        /// <summary>
        /// Select or unselect all drives in the display list
        /// Driven by the selectAllDisks check box
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void SelectAllDisks_CheckedChanged(object sender, EventArgs e)
        {   //  Entered when the 'Select all disks' check mark is changed
            //  All display items are marked as either selected or not selected
            //depending on their prior setting.
            if (selectAllDisks.Checked)
            {//swap all ready drives to selected status
                int numitems = selectListBox.Items.Count;
                for (int i = 0; i < numitems; ++i)
                    selectListBox.SetSelected(i, true);
                bool[] makeFalse = new bool[numitems];
                for (int i = 0; i < makeFalse.Length; ++i)
                    makeFalse[i] = false;
                for (int i = 0; i < numitems; ++i)
                {//count selections and store the drive character
                    String drivesSelected = selectListBox.SelectedItems[i].ToString();
                    string driveLetter = drivesSelected[0] + @":\";
                    if (FoundInIgnoreDirectory(driveLetter))
                        makeFalse[i] = true;
                    //I originally used "selectListBox.SetSelected(i, false)" instead of the makeFalse array.
                    //It caused the item after the set false to be skipped.
                }
                for (int i = 0; i < makeFalse.Length; ++i)
                    if (makeFalse[i])
                        selectListBox.SetSelected(i, false);
            }
            else
                selectListBox.ClearSelected();
        }

        /// <summary>
        /// determines if a directory has been excluded
        /// </summary>
        /// <param name="directoryInfo">directory under consideration</param>
        /// <returns>true if the directory is to be ignored</returns>
        private bool FoundInIgnoreDirectory(string driveLetter)
        {   //This routine is repeated in several classes.
            //This version does not have hidden file logic.
            if (String.IsNullOrEmpty(driveLetter) || (driveLetter.Length < 3))
                return true;
            string fwdSlash = driveLetter.Replace('\\', '/');
            foreach (string str in ignoreFolders)
            {
                if (':' == str[1])
                {   //fully qualified folder name by drive?
                    if (Char.IsLetter(str[0]))
                    {
                        string folder_str = str.Replace('\\', '/');
                        if (string.Compare(folder_str, fwdSlash, true) == 0)
                            return true;
                    }
                }
                if (string.Compare(str, fwdSlash, true) == 0)
                    return true;
            }
            return false;
        }   //ends private bool FoundInIgnoreDirectory(...

        /// <summary>
        /// Ignore any changes and exit the disk selection form
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void CancelBbutton_Click(object sender, EventArgs e)
        { this.Close(); }

        /// return DialogResult.Yes if all drives were selected
        /// return DialogResult.No if some drives were selected
        /// return DialogResult.Abort if no drives were selected
        private void exitButton_Click(object sender, EventArgs e)
        {
            selected = new ArrayList();
            if (-1 != selectListBox.SelectedIndex)
            {//determine which drives have been selected
                for (int i = 0; i < selectListBox.SelectedItems.Count; ++i)
                {//count selections and store the drive character
                    String selectedDrive = selectListBox.SelectedItems[i].ToString();
                    string ds = selectedDrive.Substring(0, selectedDrive.IndexOf("\\") + 1);
                    selected.Add(ds);
                }
                this.DialogResult = DialogResult.No;
            }
            ConfigInfo configInfo = new ConfigInfo();
            if (0 == selected.Count)
            {
                //MessageBox.Show("No drives were selected",
                //        configInfo.ProductName, MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
                this.DialogResult = DialogResult.Abort;
                //return;
            }
            else
            {
                if (selectListBox.Items.Count == selected.Count)
                    this.DialogResult = DialogResult.Yes;
                configInfo.SelectedDisks = selected;    //return selected disks via ConfigInfo class
            }
            this.Close();
        }
    }
}