// For complete examples and data files, please go to https://github.com/aspose-diagram/Aspose.Diagram-for-Java
// The path to the documents directory.
String dataDir = Utils.getDataDir(AddWindowElementInVisio.class); 
// load source Visio diagram
Diagram diagram = new Diagram(dataDir + "Drawing1.vsdx");
// initialize window object
Window window = new Window();
// set window state
window.setWindowState(WindowStateValue.MAXIMIZED);
// set window height
window.setWindowHeight(500);
// set window width
window.setWindowWidth(500);
// set window type
window.setWindowType(WindowTypeValue.STENCIL);
// add window object
diagram.getWindows().add(window);

// save in any supported format
diagram.save(dataDir + "AddWindowElementInVisio_Out.vsdx", SaveFileFormat.VSDX);