add_button.setLayoutData(new GridData(GridData.FILL_HORIZONTAL));
add_button.setAlignment(SWT.LEFT);
add_button.addSelectionListener(new SelectionAdapter() {
public void widgetSelected(SelectionEvent event) {
DirectoryDialog dir_dialog = new DirectoryDialog (getShell(),SWT.MULTI | SWT.OPEN);
String directory = dir_dialog.open();
if (directory == null) return ;
java.util.List<File> shared_dirs = null;
try {
shared_dirs = config_manager.getSharedFolders();
} catch (ConfigurationManagerException e) {