Button setChartBook;
public void onClick$setChartBook() {
Importer importer = Importers.getImporter("excel");
final InputStream is = Sessions.getCurrent().getWebApp().getResourceAsStream("/xls/graficas.xlsx");
Book book = importer.imports(is, "graficas.xlsx");
spreadsheet.setBook(book);
}
public void onClick$invalidateSpreadsheetBtn() {
spreadsheet.invalidate();