private ISelectionListener listener = new ISelectionListener() {
	
	@Override
	public void selectionChanged(IWorkbenchPart part, ISelection selection) {
		if(part instanceof WordOleEditor) {
			WordOleEditor editor = (WordOleEditor)part;
			String activeDocument = editor.getEditorInput().getName();
			if(!backup.containsKey(activeDocument)) {
				System.out.println(activeDocument + " is new");
				viewer.setInput(getInput());
			} else {
				if(!editor.inputChanged()) {
					System.out.println(activeDocument + " is the same");
				} else {
					System.out.println(activeDocument + " has changed!");
					viewer.setInput(updateInput());
				}
			}
			viewer.expandToLevel(AbstractTreeViewer.ALL_LEVELS);
			viewer.refresh();
		}
	}
};

...
Variant activeDocument = null;
OleAutomation auto = new OleAutomation(oleClientSite);
int[] appId = auto.getIDsOfNames(new String[]{ "Application" });
if (appId != null) {
    Variant vApp = auto.getProperty(appId[0]);
    if (vApp != null) {
        OleAutomation application = vApp.getAutomation();
        if(application!=null){
			int[] activeId = getId(application, "ActiveDocument");
			if(activeId != null){
				activeDocument = application.getProperty(activeId[0]);
			}
			application.dispose();
		}
    }
}
auto.dispose();
...