@Override
	protected void addTreeListeners() {
		super.addTreeListeners();

		treePanel.addTreeSelectionListener(e -> {
			if (historyPanel != null) {
				DomainFile df = treePanel.getSelectedDomainFile();
				historyPanel.setDomainFile(df);
			}
			updateOkTooltip();
		});
	}
Return the selected version number from the history panel.
@return -1 if a version history was not selected
Ghidra/Features/Base/src/main/java/ghidra/framework/main/OpenVersionedFileDialog.java