FULL PRODUCT VERSION :
java version "1.8.0_121"
Java(TM) SE Runtime Environment (build 1.8.0_121-b13)
Java HotSpot(TM) 64-Bit Server VM (build 25.121-b13, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
Windows 10 Pro

A DESCRIPTION OF THE PROBLEM :
When adding a lot of columns (> 100) to my TreeTableView, the scrollbar is calculated wrong and cutting of the last column. I created a SO-Questions and it seems to be solved in Java9 ea. But I would need this working in Java8 for my customer.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
import javafx.application.Application;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.control.TreeItem;
import javafx.scene.control.TreeTableColumn;
import javafx.scene.control.TreeTableView;
import javafx.scene.layout.Priority;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

public class TreeTableViewScroll extends Application {

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

    @Override
    public void start(final Stage primaryStage) throws Exception {
        final Scene scene = createScene();

        primaryStage.setTitle("Tree Table View Scroll");
        primaryStage.setScene(scene);
        primaryStage.show();
    }

    private Scene createScene() {
        final VBox vBox = new VBox();
        vBox.setPadding(new Insets(5));
        vBox.setSpacing(5);

        final TreeTableView<String> resultsTable = new TreeTableView<>();
        resultsTable.setShowRoot(false);
        final TreeItem<String> rootItem = new TreeItem<>();
        resultsTable.setRoot(rootItem);

        for (int i = 0; i < 200; i++) {
            final TreeTableColumn<String, String> dummyColumn = new TreeTableColumn<>("Long Column name " + i);
            resultsTable.getColumns().add(dummyColumn);
        }

        final TreeTableColumn<String, String> nameColumn = new TreeTableColumn<>("Name_very long column text");
        resultsTable.getColumns().add(nameColumn);

        vBox.getChildren().setAll(resultsTable);
        VBox.setVgrow(resultsTable, Priority.ALWAYS);
        vBox.setPrefSize(800, 600);

        for (int i = 0; i < 50; i++) {
            final TreeItem<String> newItem = new TreeItem<>("Text " + i);
            rootItem.getChildren().add(newItem);
            newItem.getChildren().add(new TreeItem<>("Text " + i));
        }

        return new Scene(vBox);
    }
}

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
http://stackoverflow.com/questions/43520674/javafx-treetableview-calculating-scrollbar-wrong/43523995#43523995

Both the actual and expected results are shown there as images (did find a way to add them here - so I simple put the so-link here).

REPRODUCIBILITY :
This bug can be reproduced always.