private void deleteLabelCommand(IPlainTextAnnotationProperty prop) {
   latestCommand.addCommand(new LabelDeletionCommand(prop));
   this.okButton.setEnabled(true);
 }
 private void addCommand(IAnnotationProperty prop, Object newValue) {
   latestCommand.addCommand(new ChangeAnnotationPropertyCommand(prop, newValue));
   this.okButton.setEnabled(true);
 }
 private void createLabelCommand(IPlainTextAnnotationProperty prop) {
   latestCommand.addCommand(new LabelCreationCommand(prop, this.labelPosCalc));
   this.okButton.setEnabled(true);
 }