SWT Tree double click 시 펼쳐지는 기능 구현

//// treeViewer.addDoubleClickListener(new DoubleClickListener()); /// private class DoubleClickListener implements IDoubleClickListener { @Override public void doubleClick(final DoubleClickEvent event) { final IStructuredSelection selection = (IStructuredSelection)event.getSelection(); if (selection == null || selection.isEmpty()) return; final Object sel = selection.getFirstElement(); final ITreeContentProvider provider = (ITreeContentProvider)treeViewer.getContentProvider(); if (!provider.hasChildren(sel)) return; if (treeViewer.getExpandedState(sel)) treeViewer.collapseToLevel(sel, AbstractTreeViewer.ALL_LEVELS); else treeViewer.expandToLevel(sel, 1); } } ,