private void Form1_Load(object sender, EventArgs e)
{
    StiOptions.Viewer.Windows.ReportSaveLoadPath = "c:\\";
    StiOptions.Designer.ReportSaveLoadPath = "c:\\";
    StiReport report = new StiReport();
    report = new StiReport();

    // you can also hide Save As button
    //StiMainMenuService mainMenuService = StiMainMenuService.GetService();
    //mainMenuService.ShowFileReportSaveAs = false;

    StiDesigner.SavingReport += new StiSavingObjectEventHandler(On_SavingReport);
    StiDesigner.DontAskSaveReport = true;
    report.Design();

}


private void On_SavingReport(object sender, StiSavingObjectEventArgs e)
{
    StiReport report = (sender as StiDesignerControl).Report;
   
    // Checking if the filename to save is known or not
    // If you set static option StiDesigner.DontAskSaveReport = true, then e.SaveAs is true only when SaveAs button is pressed.
    if (e.SaveAs == true)
    {
        SaveFileDialog mySaveDialog = new SaveFileDialog();
        mySaveDialog.InitialDirectory = "D:\\";
        mySaveDialog.DefaultExt = ".mrt";
        mySaveDialog.FileName = Path.GetFileNameWithoutExtension((sender as StiDesignerControl).ReportFileName);
        do
        {
            if (mySaveDialog.ShowDialog() == DialogResult.OK)
            {
                if (Path.GetDirectoryName(mySaveDialog.FileName) == mySaveDialog.InitialDirectory)
                {
                    report.Save(mySaveDialog.FileName);
                    MessageBox.Show("Saving complete.");
                    (sender as StiDesignerControl).ReportFileName = mySaveDialog.FileName;
                    e.Processed = true;
                }
                else
                {
                    MessageBox.Show("You can save the report only in " + mySaveDialog.InitialDirectory.ToString() + " folder.");
                }
            }
            else
            {
                break;
            }
        }
        while (Path.GetDirectoryName(mySaveDialog.FileName) != mySaveDialog.InitialDirectory);
    }
    else
    {
        //Here is the code which fires after the filename had been set to the specified folder
        report.Save(report.ReportFile);
    }
}