private void showHistoryPanel(boolean showHistory) {
		historyIsShowing = showHistory;
		if (showHistory) {
			createHistoryPanel();
			historyButton.setText("Hide History");
			DomainFile df = treePanel.getSelectedDomainFile();
			historyPanel.setDomainFile(df);
			splitPane.setDividerSize(DIVIDER_SIZE);
			splitPane.setDividerLocation(DEFAULT_WIDTH_NO_HISTORY - 4);
		}
		else {
			historyButton.setText("Show History>>");
			splitPane.setDividerSize(0);
			splitPane.setRightComponent(null);
			historyPanel = null;
		}

		Dimension size = getPreferredSizeForHistoryState();
		rootPanel.setPreferredSize(size);
		repack();
	}
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