public interface IProgressDialog

        /// <param name="dwLineNum">The line number on which the text is to be displayed. Currently there are three lines—1, 2, and 3. If the PROGDLG_AUTOTIME flag was included in the dwFlags parameter when IProgressDialog::StartProgressDialog was called, only lines 1 and 2 can be used. The estimated time will be displayed on line 3.</param>

        /// IProgressDialog::StopProgressDialog to close the dialog box. The application must wait until the

        /// next time it calls IProgressDialog::HasUserCancelled to discover that the user has canceled the

        /// calls IProgressDialog::StartProgressDialog. Unless your application will start immediately,

        /// should not be called after the first call to IProgressDialog::SetProgress.</remarks>

IProgressDialog pd = (IProgressDialog)new ProgressDialog();

http://pietschsoft.com/post/2009/08/17/CSharp-IProgressDialog-Show-Native-Progress-Dialog-from-dotNet-in-Windows.aspx

    /// <remarks>If this flag is set, IProgressDialog::SetLine can be used only to display text on lines 1 and 2.</remarks>

    /// <remarks>Typically, an application can quantitatively determine how much of the operation remains and periodically pass that value to IProgressDialog::SetProgress. The progress dialog box uses this information to update its progress bar. This flag is typically set when the calling application must wait for an operation to finish, but does not have any quantitative information it can use to update the dialog box.</remarks>

    ''' <remarks>If this flag is set, IProgressDialog::SetLine can be used only to display text on lines 1 and 2.</remarks>

    ''' <remarks>Typically, an application can quantitatively determine how much of the operation remains and periodically pass that value to IProgressDialog::SetProgress. The progress dialog box uses this information to update its progress bar. This flag is typically set when the calling application must wait for an operation to finish, but does not have any quantitative information it can use to update the dialog box.</remarks>