TreeTableView's scrolling range is calculated incorrectly. To reproduce expand the root for the sample below.

import javafx.application.Application;
import javafx.beans.property.ReadOnlyStringWrapper;
import javafx.beans.value.ObservableValue;
import javafx.scene.Scene;
import javafx.scene.control.TreeItem;
import javafx.scene.control.TreeTableColumn;
import javafx.scene.control.TreeTableView;
import javafx.stage.Stage;
import javafx.util.Callback;

public class App extends Application {

    public static void main(String[] args) {
        launch(args);
    }

    @Override
    public void start(Stage stage) throws Exception {
        TreeTableView<String> control = new TreeTableView<String>();
        TreeTableColumn<String, String> column = new TreeTableColumn<String, String>("Column 0");
        control.getColumns().add(column);
        column.setCellValueFactory(new Callback<TreeTableColumn.CellDataFeatures<String, String>, ObservableValue<String>>() {
            @Override
            public ObservableValue<String> call(TreeTableColumn.CellDataFeatures<String, String> p) {
                return new ReadOnlyStringWrapper(p.getValue().getValue());
            }
        });
        TreeItem<String> root = new TreeItem<String>("Root");
        control.setRoot(root);
        for (int i = 0; i < 20; i++) {
            TreeItem<String> item = new TreeItem<String>("Item " + i);
            root.getChildren().add(item);
        }
        stage.setScene(new Scene(control));
        stage.show();
    }
}