/// <summary>
        /// Shows the dialog box to let the user browse for and select a folder.
        /// </summary>
        /// <param name="parentWindowHandle">The HWND of the parent window.</param>
        /// <returns>The selected folder or <c>null</c> if no folder was selected by the user.</returns>
        protected override bool RunDialog(IntPtr parentWindowHandle)
        {
            // Make sure OLE is initialized. This is a prerequisite for calling SHBrowseForFolder.
            NativeMethods.OleInitialize(IntPtr.Zero);

            IntPtr rpidl = IntPtr.Zero;

            NativeMethods.SHGetSpecialFolderLocation(parentWindowHandle, (int)RootFolder, out rpidl);
            if (rpidl == IntPtr.Zero)
            {
                NativeMethods.SHGetSpecialFolderLocation(parentWindowHandle, 0, out rpidl);
                if (rpidl == IntPtr.Zero)
                {
                    throw new InvalidOperationException("No root folder specified for FolderBrowserDialog2.");
                }
            }

            if (Control.CheckForIllegalCrossThreadCalls && (Application.OleRequired() != System.Threading.ApartmentState.STA))
            {
                throw new System.Threading.ThreadStateException("Debugging Exception Only. Thread must be STA.");
            }

            BrowseInfoFlag browseInfoFlag = BrowseInfoFlag.BIF_NEWDIALOGSTYLE | BrowseInfoFlag.BIF_SHAREABLE;

            if (!ShowNewFolderButton)
            {
                browseInfoFlag |= BrowseInfoFlag.BIF_NONEWFOLDERBUTTON;
            }
            if (ShowFolderPathEditBox)
            {
                browseInfoFlag |= BrowseInfoFlag.BIF_EDITBOX | BrowseInfoFlag.BIF_VALIDATE;
            }
            if (ShowFiles)
            {
                browseInfoFlag |= BrowseInfoFlag.BIF_BROWSEINCLUDEFILES;
            }
            browseInfoFlag |= (BrowseInfoFlag)BrowserFlag;

            NativeMethods.BROWSEINFO bi;
            bi.hwndOwner      = parentWindowHandle;
            bi.pidlRoot       = rpidl;
            bi.pszDisplayName = new string('\0', 260);
            bi.lpszTitle      = Description;
            bi.ulFlags        = (uint)browseInfoFlag;
            bi.lpfn           = new NativeMethods.BrowseCallBackProc(OnBrowseEvent);
            bi.lParam         = IntPtr.Zero;
            bi.iImage         = 0;

            StringBuilder sb   = new StringBuilder(260);
            IntPtr        pidl = IntPtr.Zero;

            try
            {
                pidl = NativeMethods.SHBrowseForFolder(ref bi);
                if (((browseInfoFlag & BrowseInfoFlag.BIF_BROWSEFORPRINTER) == BrowseInfoFlag.BIF_BROWSEFORPRINTER) ||
                    ((browseInfoFlag & BrowseInfoFlag.BIF_BROWSEFORCOMPUTER) == BrowseInfoFlag.BIF_BROWSEFORCOMPUTER))
                {
                    SelectedPath = bi.pszDisplayName;
                }
                else
                {
                    if (pidl == IntPtr.Zero || 0 == NativeMethods.SHGetPathFromIDList(pidl, sb))
                    {
                        return(false);
                    }
                    SelectedPath = sb.ToString();
                }
                return(true);
            }
            finally
            {
                if (rpidl != IntPtr.Zero)
                {
                    Marshal.FreeCoTaskMem(rpidl);
                }
                if (pidl != IntPtr.Zero)
                {
                    Marshal.FreeCoTaskMem(pidl);
                }
            }
        }