Slider Pane implementation for JavaFX.

SliderPane.java

import javafx.animation.*;
import javafx.beans.property.*;
import javafx.scene.Node;
import javafx.scene.layout.Pane;
import javafx.util.Duration;

public class SliderPane extends Pane{
    public SliderPane(){
    }

    public SliderPane(Node... children){
        super(children);
    }

    private final IntegerProperty openedIndex = new SimpleIntegerProperty(0);
    {
        openedIndex.addListener((obs, o, n) -> openedIndexChanged(o.intValue(), n.intValue()));
    }

    public final int getOpenedIndex(){
        return openedIndex.get();
    }
    public final IntegerProperty openedIndexProperty(){
        return openedIndex;
    }
    public final void setOpenedIndex(int openedIndex){
        this.openedIndex.set(openedIndex);
    }

    private final BooleanProperty animated = new SimpleBooleanProperty(false);

    public final boolean isAnimated(){
        return animated.get();
    }

    public final BooleanProperty animatedProperty(){
        return animated;
    }

    public final void setAnimated(boolean animated){
        this.animated.set(animated);
    }

    private final IntegerProperty animationTime = new SimpleIntegerProperty(1000);

    public final int getAnimationTime(){
        return animationTime.get();
    }
    public final IntegerProperty animationTimeProperty(){
        return animationTime;
    }
    public final void setAnimationTime(int animationTime){
        this.animationTime.set(animationTime);
    }


    private final ReadOnlyBooleanWrapper animating = new ReadOnlyBooleanWrapper(false);

    public final boolean isAnimating(){
        return animating.get();
    }
    public final ReadOnlyBooleanProperty animatingProperty(){
        return animating.getReadOnlyProperty();
    }

    private double offsetIndex;

    private Timeline timeline;

    private void openedIndexChanged(int oldIndex, int newIndex){
        if(isAnimated()){
            if(timeline != null){
                timeline.stop();
            }
            DoubleProperty percentProperty = new SimpleDoubleProperty(0);
            timeline = new Timeline(new KeyFrame(Duration.millis(getAnimationTime()), new KeyValue(percentProperty, 1.0)));
            timeline.statusProperty().addListener((obs, o, n) -> {
                animating.set(n == Animation.Status.RUNNING);
            });

            percentProperty.addListener((obs, o, n) -> {
                if(isAnimated()){
                    offsetIndex = Interpolator.EASE_OUT.interpolate((double)oldIndex, newIndex, n.doubleValue());
                }
                else{
                    timeline.stop();
                    offsetIndex = newIndex;
                }
                requestLayout();
            });

            timeline.play();
        }
        else{
            offsetIndex = newIndex;
            layoutChildren();
        }
    }

    @Override
    protected void layoutChildren(){
        super.layoutChildren();

        double width = getWidth();
        double height = getHeight();

        int i = 0;
        for(Node node : getManagedChildren()){
            node.resizeRelocate((width * i++) - (offsetIndex * width), 0, width, height);
        }
    }
}

SliderPaneUsage.java

import javafx.application.Application;
import javafx.collections.FXCollections;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.ListView;
import javafx.scene.control.TextField;
import javafx.scene.layout.HBox;
import javafx.scene.layout.Priority;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

public class SliderPaneUsage extends Application{
    private static final int PROJECT_LIST_INDEX = 0;
    private static final int CREATE_PROJECT_INDEX = 1;

    private SliderPane root;

    @Override
    public void start(Stage stage) throws Exception{
        final ListView<String> projectsList = new ListView<>(FXCollections.observableArrayList("Project 1", "Project 2", "Project 3"));

        final HBox controlsWrapper;
        {
            final Button createProjectButton = new Button("Create project");
            createProjectButton.setOnAction((e) -> root.setOpenedIndex(CREATE_PROJECT_INDEX));
            controlsWrapper = new HBox(createProjectButton);
            controlsWrapper.setPadding(new Insets(4));
        }

        VBox projectListWrapper = new VBox(projectsList, controlsWrapper);
        VBox.setVgrow(projectsList, Priority.ALWAYS);

        final VBox createProjectWrapper;
        {
            final TextField projectNameField = new TextField();
            projectNameField.setPromptText("Project name");

            final Button cancelButton = new Button("Cancel");
            cancelButton.setOnAction((e) -> root.setOpenedIndex(PROJECT_LIST_INDEX));

            final Button createButton = new Button("Create");
            createButton.setOnAction((e) -> {
                projectsList.getItems().add(projectNameField.getText());
                root.setOpenedIndex(PROJECT_LIST_INDEX);
            });

            VBox fieldsWrapper = new VBox(projectNameField);
            VBox.setVgrow(fieldsWrapper, Priority.ALWAYS);

            final HBox buttonsWrapper = new HBox(cancelButton, createButton);
            buttonsWrapper.setSpacing(4);
            buttonsWrapper.setAlignment(Pos.CENTER_RIGHT);

            createProjectWrapper = new VBox(fieldsWrapper, buttonsWrapper);
        }

        root = new SliderPane(projectListWrapper, createProjectWrapper);
        root.setAnimated(true);
        root.setAnimationTime(500);
        root.getChildren().forEach((node) -> node.disableProperty().bind(root.animatingProperty()));

        stage.setScene(new Scene(root, 640, 480));
        stage.show();
    }

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