@Override
		public Object getTransferData(List<GTreeNode> transferNodes, DataFlavor flavor)
				throws UnsupportedFlavorException {
			if (flavor != DataFlavor.stringFlavor) {
				throw new UnsupportedFlavorException(flavor);
			}
			if (transferNodes.isEmpty()) {
				return null;
			}
			if (transferNodes.size() == 1) {
				GTreeNode node = transferNodes.get(0);
				if (node instanceof NodeWithText) {
					return ((NodeWithText) node).collectReportText(transferNodes, 0).trim();
				}
				return null;
			}
			return root.collectReportText(transferNodes, 0).trim();
		}
This spacer addresses the optical impression that the message panel changes size when showing details
Ghidra/Framework/Docking/src/main/java/docking/ErrLogExpandableDialog.java