Object node = SelectionUtil.getSingleElement(viewer.getSelection());
if (node instanceof AspectNode && event.detail == DND.DROP_MOVE) {
AspectNode aspect = (AspectNode) node;
if (event.detail == DND.DROP_MOVE) {
try {
aspect.withdraw();
} catch (UnreachableException e) {
ProsePlugin.log(e);
ProsePlugin.openErrorDialog("Aspect withdrawal failed",
"Could not withdraw aspect because the Prose application is not reachable.");
}