private void updateOkTooltip() {
		String tip;
		if (usingOpenProgramList()) {
			tip = "Use selected " + domainObjectClass.getSimpleName();
		}
		else {
			tip = "Open the selected file";
			if (historyPanel != null && historyIsShowing) {
				int versionNumber = historyPanel.getSelectedVersionNumber();
				if (versionNumber >= 0) {
					DomainFile df = OpenVersionedFileDialog.super.getDomainFile();
					okButton.setToolTipText(
						"Open version " + versionNumber + " for " + df.getName());
				}
			}
		}
		okButton.setToolTipText(tip);
	}
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