private boolean usingOpenProgramList() {
		return tabbedPane != null &&
			tabbedPane.getModel().getSelectedIndex() == OPEN_OBJECT_LIST_TAB;
	}
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