怎样控制powerpoint全屏幕运行啊?

PowerPoint.Application app = new PowerPoint.ApplicationClass(); app.Visible = Office.MsoTriState.msoTrue;
Presentation pres =  app.Presentations.Open( path, Office.MsoTriState.msoFalse, Office.MsoTriState.msoTrue,
Office.MsoTriState.msoTrue ); // we jump between slides ourselves
pres.SlideShowSettings.AdvanceMode = PpSlideShowAdvanceMode.ppSlideShowManualAdvance;

// we want the whole slide and do not want to wait for any transitions
pres.SlideShowSettings.ShowWithAnimation = Office.MsoTriState.msoFalse;

// start the show just to fill the screen
app.ActivePresentation.SlideShowSettings.Run();