@Override
		protected Transferable createTransferable(JComponent c) {
			ArrayList<GTreeNode> nodes = new ArrayList<>();
			for (TreePath path : ((JTree) c).getSelectionPaths()) {
				nodes.add((GTreeNode) path.getLastPathComponent());
			}
			try {
				return new StringSelection(
					(String) getTransferData(nodes, DataFlavor.stringFlavor));
			}
			catch (UnsupportedFlavorException e) {
				Msg.debug(this, e.getMessage(), e);
			}
			return null;
		}
This spacer addresses the optical impression that the message panel changes size when showing details
Ghidra/Framework/Docking/src/main/java/docking/ErrLogExpandableDialog.java