@Override
protected void event(UserRequest ureq, Component source, Event event) {
if (source == showFileButton){
File exportFile = new File(exportDir, targetFileName);
MediaResource resource = new MimedFileMediaResource(exportFile, "application/vnd.ms-excel; charset="+charset, true);
ureq.getDispatchResult().setResultingMediaResource(resource);
showFileButton.setDirty(false);
}
}