Bug 304926 [CommonNavigator] TextActionHandler in o.e.navigator.resources is a poor duplicate of the good one
It looks like this was copied from the real one in org.eclipse.ui.ide when the CNF was created because it needed an updateActionBars() method. Everything else is the same, except they have actually diverged due to many fixes from Paul last year. I will modify the original to add the required method and refer to the original.
bundles/org.eclipse.ui.ide/extensions/org/eclipse/ui/actions/TextActionHandler.java
textSelectAllAction);
    private Listener textControlListener = new TextControlListener();
    private Text activeTextControl;
    private MouseAdapter mouseAdapter = new MouseAdapter() {
        public void mouseUp(MouseEvent e) {
            updateActionsEnableState();
        }
    };
    private KeyAdapter keyAdapter = new KeyAdapter() {
        public void keyReleased(KeyEvent e) {
            updateActionsEnableState();
        }
    };
    private class TextControlListener implements Listener {
        public void handleEvent(Event event) {
            switch (event.type) {
            case SWT.Activate:
                activeTextControl = (Text) event.widget;
                updateActionsEnableState();
                break;
            case SWT.Deactivate:
                activeTextControl = null;
                updateActionsEnableState();
                break;
            default:
                break;
            }
        }
    }
    private class PropertyChangeListener implements IPropertyChangeListener {