public void widgetDefaultSelected(SelectionEvent e) {
}
public void widgetSelected(SelectionEvent e) {
if (e.getSource() == openPreferences) {
PreferenceManager manager = new PreferenceManager();
manager.addToRoot(new PreferenceNode("Hadoop Installation Directory",
new HadoopHomeDirPreferencePage()));
PreferenceDialog dialog = new PreferenceDialog(this.getShell(), manager);
dialog.create();
dialog.setMessage("Select Hadoop Installation Directory");
dialog.setBlockOnOpen(true);