Resizing a node and make children appear/disappear on its "visibility"

Question

I guees I could wrap the question within a smaller sample code snippet. On the other side I put the whole thing in here, so you can see what I am working on (should be complete an runnable).
I am playing around with some sort of windowing within JavaFX (building my own windows).
It does not look nice so far, but it works somehow. Anyhow, when I minimize the window by dragging the frame it will be minimized till the size of its children. I would like to get it as small as I want. Uncommenting the Line " //window.setMinSize(0.0, 0.0);" will let me make it as small as possible, BUT the children stay visible too, but they should dissapear as soon as the frame hits their bounds.
Anybody having any idea for a nice/slick solution ?
Here is the code:
package org.rob.javafx.framework;
import javafx.application.Application;
import javafx.event.EventHandler;
import javafx.geometry.Point2D;
import javafx.scene.Cursor;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.ButtonBuilder;
import javafx.scene.control.Label;
import javafx.scene.control.LabelBuilder;
import javafx.scene.input.MouseEvent;
import javafx.scene.layout.*;
import javafx.stage.Stage;
import javafx.stage.StageStyle;
public class Tests  extends Application {
    private Stage primaryStage;
    private double titleBox_initX;
    private double titleBox_initY;
    private Point2D titleBox_dragAnchor;
    private boolean resize_dragStart = false;
    private double resize_initWidth;
    private double resize_initHeight;
    private double resize_initX;
    private double resize_initY;
    private int resize_edge = EDGE_NONE;
    private Point2D resize_dragAnchor;
    private boolean izing_isMax = false;
    private double izing_X;
    private double izing_Y;
    private double izing_Width;
    private double izing_Height;
    private void init(Stage primaryStage) {
        this.primaryStage = primaryStage;
        Group root = new Group();
        primaryStage.setResizable(true);
        primaryStage.setScene(new Scene(root, 500,500));
        primaryStage.initStyle(StageStyle.TRANSPARENT);
        final VBox centerContent = VBoxBuilder.create().children(new Label("Label1"), new Label("Label2")).build();
        final BorderPane windowContent = BorderPaneBuilder.create().center(centerContent).build();
        final Region windowContentBox = HBoxBuilder.create().children(windowContent).build();
        final Region window = createWindow("Blue circle", windowContentBox, root);
        window.setTranslateX(200);
        window.setTranslateY(80);
    private Region createWindow(final String title, final Region content, final Group parent) {
        final StackPane window = StackPaneBuilder.create().prefHeight(300).cursor(Cursor.HAND).prefWidth(200).style("-fx-background-color:#b0c4de; -fx-border-style:solid; -fx-border-width:6px; -fx-border-color: linear-gradient(to bottom right, gray, gray 50%, black 50%, black);").build();
        // Without : minimizing stops at the space the children need, with this you can make it as small as possible,
        // BUT the children are still visible. -> ToDo: Make the children dissapear, but keep the titlebar.
        //window.setMinSize(0.0, 0.0);
        // Title-Bar
        final Label titleLabel = LabelBuilder.create().text(title).style("-fx-text-fill:yellow;").build();
        final Region titleBoxSpring = new Region();
        titleBoxSpring.setPrefWidth(20);
        titleBoxSpring.setMinWidth(Region.USE_PREF_SIZE);
        final Button titleMinBtn = ButtonBuilder.create().text("_").cursor(Cursor.DEFAULT).build();
        final Button titleMaxBtn = ButtonBuilder.create().text("+").cursor(Cursor.DEFAULT).build();
        final Button titleCloseBtn = ButtonBuilder.create().text("X").cursor(Cursor.DEFAULT).build();
        HBox.setHgrow(titleBoxSpring, Priority.ALWAYS); // make the "spring" always grow, so the buttons are always on the right.
        final HBox titleResizeButtonBox = HBoxBuilder.create().spacing(2).children(titleMinBtn, titleMaxBtn, titleCloseBtn).style("-fx-alignment:center-right;").build();
        final HBox titleBox = HBoxBuilder.create().children(titleLabel,titleBoxSpring,titleResizeButtonBox).prefHeight(30).cursor(Cursor.HAND).spacing(4.0).style("-fx-alignment:center-left; -fx-background-color:blue; -fx-border-style:dashed; -fx-border-width:1px; -fx-border-color: linear-gradient(to bottom right, gray, gray 50%, black 50%, black);").build();
        final BorderPane windowContentPane = BorderPaneBuilder.create().top(titleBox).center(content).build();
        titleMinBtn.setOnMouseClicked(new EventHandler<MouseEvent>() {
            public void handle(MouseEvent me) {
                // -------- Minimizing-Handling ------
                if(izing_isMax)
                    maximizeItRevert(window);
                else
                    minimizeIt(window);            }
        titleMaxBtn.setOnMouseClicked(new EventHandler<MouseEvent>() {
            public void handle(MouseEvent me) {
                // -------- Maximize-Handling ------
                if(izing_isMax)
                    maximizeItRevert(window);
                else
                    maximizeIt(window);
        titleCloseBtn.setOnMouseClicked(new EventHandler<MouseEvent>() {
            public void handle(MouseEvent me) {
                parent.getChildren().remove(window);
        titleBox.setOnMouseClicked(new EventHandler<MouseEvent>() {
            public void handle(MouseEvent me) {
                switch(me.getClickCount()){
                    case 1:
                        break;
                    case 2:
                        // -------- Maximize-Handling ------
                        if(izing_isMax)
                            maximizeItRevert(window);
                        else
                            maximizeIt(window);
                        break;
                    default:
                        break;
                //when mouse is pressed, store initial position
                titleBox_initX = window.getTranslateX();
                titleBox_initY = window.getTranslateY();
                titleBox_dragAnchor = new Point2D(me.getSceneX(), me.getSceneY());
        titleBox.setOnMousePressed(new EventHandler<MouseEvent>() {
            public void handle(MouseEvent me) {
                //when mouse is pressed, store initial position
                titleBox_initX = window.getTranslateX();
                titleBox_initY = window.getTranslateY();
                titleBox_dragAnchor = new Point2D(me.getSceneX(), me.getSceneY());
        titleBox.setOnMouseDragged(new EventHandler<MouseEvent>() {
            public void handle(MouseEvent me) {
                if(!izing_isMax){
                    double dragX = me.getSceneX() - titleBox_dragAnchor.getX();
                    double dragY = me.getSceneY() - titleBox_dragAnchor.getY();
                    double newXPosition = titleBox_initX + dragX;
                    double newYPosition = titleBox_initY + dragY;
                    window.setTranslateX(newXPosition);
                    window.setTranslateY(newYPosition);
        window.setOnMouseExited(new EventHandler<MouseEvent>() {
            public void handle(MouseEvent me) {
                if(window.getCursor() != Cursor.DEFAULT)
                    window.setCursor(Cursor.DEFAULT);
        window.setOnMouseMoved(new EventHandler<MouseEvent>() {
            public void handle(MouseEvent me) {
                // ------ Resize-Handling ------
                int resize_edge = getRESIZE_EDGE(me, window);
                switch(resize_edge){
                    case EDGE_NORTH:
                        if (window.getCursor() != Cursor.N_RESIZE)
                            window.setCursor(Cursor.N_RESIZE);
                        break;
                    case EDGE_NORTH_EAST:
                        if (window.getCursor() != Cursor.NE_RESIZE)
                            window.setCursor(Cursor.NE_RESIZE);
                        break;
                    case EDGE_EAST:
                        if (window.getCursor() != Cursor.E_RESIZE)
                            window.setCursor(Cursor.E_RESIZE);
                        break;
                    case EDGE_SOUTH_EAST:
                        if (window.getCursor() != Cursor.SE_RESIZE)
                            window.setCursor(Cursor.SE_RESIZE);
                        break;
                    case EDGE_SOUTH:
                        if (window.getCursor() != Cursor.S_RESIZE)
                            window.setCursor(Cursor.S_RESIZE);
                        break;
                    case EDGE_SOUTH_WEST:
                        if (window.getCursor() != Cursor.SW_RESIZE)
                            window.setCursor(Cursor.SW_RESIZE);
                        break;
                    case EDGE_WEST:
                        if (window.getCursor() != Cursor.W_RESIZE)
                            window.setCursor(Cursor.W_RESIZE);
                        break;
                    case EDGE_NORTH_WEST:
                        if (window.getCursor() != Cursor.NW_RESIZE)
                            window.setCursor(Cursor.NW_RESIZE);
                        break;
                    default:
                        if (window.getCursor() != Cursor.DEFAULT)
                            window.setCursor(Cursor.DEFAULT);
                        break;
        window.setOnMousePressed(new EventHandler<MouseEvent>() {
            public void handle(MouseEvent me) {
                // ------ Resize-Handling ------
                resize_edge = getRESIZE_EDGE(me, window);
                if(resize_edge != EDGE_NONE){
                    resize_initX = window.getTranslateX();
                    resize_initY = window.getTranslateY();
                    resize_initWidth = window.getWidth();
                    resize_initHeight = window.getHeight();
                    resize_dragAnchor = new Point2D(me.getSceneX(), me.getSceneY());
                    resize_dragStart = true;
                } else
                    resize_dragStart = false;
        window.setOnMouseDragged(new EventHandler<MouseEvent>() {
            public void handle(MouseEvent me) {
                // ------ Resize-Handling ------
                if(resize_dragStart){
                    double dragX = me.getSceneX() - resize_dragAnchor.getX();
                    double dragY = me.getSceneY() - resize_dragAnchor.getY();
                    System.out.println("DraxX = " + dragX + " ; DragY = " + dragY);
                    double newWidth = window.getPrefWidth();
                    double newHeight = window.getPrefHeight();
                    switch(resize_edge){
                        case EDGE_NORTH:
                            newHeight = resize_initHeight - dragY;
                            window.setTranslateY(resize_initY + dragY);
                            break;
                        case EDGE_NORTH_EAST:
                            newHeight = resize_initHeight - dragY;
                            window.setTranslateY(resize_initY + dragY);
                            newWidth = resize_initWidth + dragX;
                            break;
                        case EDGE_EAST:
                            newWidth = resize_initWidth + dragX;
                            break;
                        case EDGE_SOUTH_EAST:
                            newHeight = resize_initHeight + dragY;
                            newWidth = resize_initWidth + dragX;
                            break;
                        case EDGE_SOUTH:
                            newHeight = resize_initHeight + dragY;
                            break;
                        case EDGE_SOUTH_WEST:
                            newHeight = resize_initHeight + dragY;
                            newWidth = resize_initWidth - dragX;
                            window.setTranslateX(resize_initX + dragX);
                            break;
                        case EDGE_WEST:
                            newWidth = resize_initWidth - dragX;
                            window.setTranslateX(resize_initX + dragX);
                            break;
                        case EDGE_NORTH_WEST:
                            newHeight = resize_initHeight - dragY;
                            window.setTranslateY(resize_initY + dragY);
                            newWidth = resize_initWidth - dragX;
                            window.setTranslateX(resize_initX + dragX);
                            break;
                        default:
                            break;
                    System.out.println("New-Width = " + newWidth + " ; New-Height = " + newHeight);
                    System.out.println("Content-Width = " + content.getWidth() + " ; Content-Height = " + content.getHeight());
                    window.setPrefWidth(newWidth);
                    window.setPrefHeight(newHeight);
        window.getChildren().addAll(windowContentPane);
        parent.getChildren().add(window);
        return window;
    private void maximizeItRevert(Region window){
        window.setTranslateX(izing_X);
        window.setTranslateY(izing_Y);
        window.setPrefWidth(izing_Width);
        window.setPrefHeight(izing_Height);
        izing_isMax = false;
    private void maximizeIt(Region window){
        izing_X = window.getTranslateX();
        izing_Y = window.getTranslateY();
        izing_Width = window.getWidth();
        izing_Height = window.getHeight();
        window.setTranslateX(0);
        window.setTranslateY(0);
        if(primaryStage.getStyle() == StageStyle.TRANSPARENT){
            window.setPrefWidth(window.getScene().getWindow().getWidth());
            window.setPrefHeight(window.getScene().getWindow().getHeight());
        } else {
            window.setPrefWidth(window.getScene().getWindow().getWidth() - 16);     // ToDo: 16 is hardcoded, since I do not know how to get the window border size. Still to do.
            window.setPrefHeight(window.getScene().getWindow().getHeight() - 38);   // ToDo: same
        izing_isMax = true;
    private void minimizeIt(Region window){
        izing_X = window.getTranslateX();
        izing_Y = window.getTranslateY();
        izing_Width = window.getWidth();
        izing_Height = window.getHeight();
        window.setTranslateX(0);
        if(primaryStage.getStyle() == StageStyle.TRANSPARENT)
            window.setTranslateY(window.getScene().getWindow().getHeight() - 50);
        else
            window.setTranslateY(window.getScene().getWindow().getHeight() - 88);
        window.setPrefWidth(60);
        window.setPrefHeight(30);
        izing_isMax = true;
    private final static int EDGEWITH = 8;
    private final static int EDGE_NONE = 0;
    private final static int EDGE_NORTH = 1;
    private final static int EDGE_NORTH_EAST = 2;
    private final static int EDGE_EAST = 3;
    private final static int EDGE_SOUTH_EAST = 4;
    private final static int EDGE_SOUTH = 5;
    private final static int EDGE_SOUTH_WEST = 6;
    private final static int EDGE_WEST = 7;
    private final static int EDGE_NORTH_WEST = 8;
    private int getRESIZE_EDGE(MouseEvent me, Region region){
        if(isN_RESIZE(me, region)){
            return EDGE_NORTH;   
        } else if(isNE_RESIZE(me, region)){
            return EDGE_NORTH_EAST;
        } else if(isE_RESIZE(me, region)){
            return EDGE_EAST;
        } else if(isSE_RESIZE(me, region)){
            return EDGE_SOUTH_EAST;
        } else if(isS_RESIZE(me, region)){
            return EDGE_SOUTH;
        } else if(isSW_RESIZE(me, region)){
            return EDGE_SOUTH_WEST;
        } else if(isW_RESIZE(me, region)){
            return EDGE_WEST;
        } else if(isNW_RESIZE(me, region)){
            return EDGE_NORTH_WEST;
        } else
            return EDGE_NONE;
    private boolean isN_RESIZE(MouseEvent me, Region region){       // North
        double recentXPos = me.getX();
        double recentYPos = me.getY();
        double xMin = EDGEWITH;
        double xMax = region.getWidth() - EDGEWITH;
        double yMin = 0;
        double yMax = EDGEWITH;
        return recentXPos > xMin && recentXPos < xMax && recentYPos > yMin && recentYPos < yMax;
    private boolean isNE_RESIZE(MouseEvent me, Region region){      // North-East (Upper-Right Corner)
        double recentXPos = me.getX();
        double recentYPos = me.getY();
        double xMin = region.getWidth() - EDGEWITH;
        double xMax = region.getWidth();
        double yMin = 0;
        double yMax = EDGEWITH;
        return recentXPos > xMin && recentXPos < xMax && recentYPos > yMin && recentYPos < yMax;
    private boolean isE_RESIZE(MouseEvent me, Region region){       // East
        double recentXPos = me.getX();
        double recentYPos = me.getY();
        double xMin = region.getWidth() - EDGEWITH;
        double xMax = region.getWidth();
        double yMin = EDGEWITH;
        double yMax = region.getHeight() - EDGEWITH;
        return recentXPos > xMin && recentXPos < xMax && recentYPos > yMin && recentYPos < yMax;
    private boolean isSE_RESIZE(MouseEvent me, Region region){      // South-East (Lower-Right Corner)
        double recentXPos = me.getX();
        double recentYPos = me.getY();
        double xMin = region.getWidth() - EDGEWITH;
        double xMax = region.getWidth();
        double yMin = region.getHeight() - EDGEWITH;
        double yMax = region.getHeight();
        return recentXPos > xMin && recentXPos < xMax && recentYPos > yMin && recentYPos < yMax;
    private boolean isS_RESIZE(MouseEvent me, Region region){      // South
        double recentXPos = me.getX();
        double recentYPos = me.getY();
        double xMin = EDGEWITH;
        double xMax = region.getWidth() - EDGEWITH;
        double yMin = region.getHeight() - EDGEWITH;
        double yMax = region.getHeight();
        return recentXPos > xMin && recentXPos < xMax && recentYPos > yMin && recentYPos < yMax;
    private boolean isSW_RESIZE(MouseEvent me, Region region){      // South-West (Lower-Left Corner)
        double recentXPos = me.getX();
        double recentYPos = me.getY();
        double xMin = 0;
        double xMax = EDGEWITH;
        double yMin = region.getHeight() - EDGEWITH;
        double yMax = region.getHeight();
        return recentXPos > xMin && recentXPos < xMax && recentYPos > yMin && recentYPos < yMax;
    private boolean isW_RESIZE(MouseEvent me, Region region){      // West
        double recentXPos = me.getX();
        double recentYPos = me.getY();
        double xMin = 0;
        double xMax = EDGEWITH;
        double yMin = EDGEWITH;
        double yMax = region.getHeight() - EDGEWITH;
        return recentXPos > xMin && recentXPos < xMax && recentYPos > yMin && recentYPos < yMax;
    private boolean isNW_RESIZE(MouseEvent me, Region region){      // North-West (Upper-Left Corner)
        double recentXPos = me.getX();
        double recentYPos = me.getY();
        double xMin = 0;
        double xMax = EDGEWITH;
        double yMin = 0;
        double yMax = EDGEWITH;
        return recentXPos > xMin && recentXPos < xMax && recentYPos > yMin && recentYPos < yMax;
    @Override
    public void start(Stage primaryStage) throws Exception {
        init(primaryStage);
        primaryStage.show();
    public static void main(String[] args) { launch(args); }
}

Answer 1

Hmm~ in your case I think you have to compute it by yourself
I would use the width and height of the content as dependency.
Add this to the hande-method of your MouseDragged-EventHandler:
HBox center = (HBox) ((BorderPane) ((StackPane) window).getChildren().get(0)).getCenter();
HBox top = (HBox) ((BorderPane) ((StackPane) window).getChildren().get(0)).getTop();
/** @todo: compute the border of the window into this */
if (newWidth < center.getWidth() || (newHeight - top.getHeight()) < center.getHeight()) {
    center.setManaged(false);
    center.setVisible(false);
else {
    center.setManaged(true);
    center.setVisible(true);
}