dialog.setTitle(RESOURCE_BUNDLE.getString("OpenFile")); dialog.getDialogPane().getButtonTypes().addAll(ButtonType.OK, ButtonType.CANCEL); NodeChooser<N, F, D, T> nodeChooser = new NodeChooser<>(window, treeModel, appData, context, filter, openedProjectsList); Button button = (Button) dialog.getDialogPane().lookupButton(ButtonType.OK); button.disableProperty().bind(nodeChooser.selectedNodeProperty().isNull());