DragResizercan be used to add mouse listeners to a Region and make it resizable by the user by clicking and dragging the border in the same way as a window. Only height resizing is currently implemented.

DragResizer.java

import javafx.event.EventHandler;
import javafx.scene.Cursor;
import javafx.scene.input.MouseEvent;
import javafx.scene.layout.Region;

/**
 * {@link DragResizer} can be used to add mouse listeners to a {@link Region}
 * and make it resizable by the user by clicking and dragging the border in the
 * same way as a window.
 * <p>
 * Only height resizing is currently implemented. Usage: <pre>DragResizer.makeResizable(myAnchorPane);</pre>
 * 
 * @author atill
 * 
 */
public class DragResizer {
    
    /**
     * The margin around the control that a user can click in to start resizing
     * the region.
     */
    private static final int RESIZE_MARGIN = 5;

    private final Region region;

    private double y;
    
    private boolean initMinHeight;
    
    private boolean dragging;
    
    private DragResizer(Region aRegion) {
        region = aRegion;
    }

    public static void makeResizable(Region region) {
        final DragResizer resizer = new DragResizer(region);
        
        region.setOnMousePressed(new EventHandler<MouseEvent>() {
            @Override
            public void handle(MouseEvent event) {
                resizer.mousePressed(event);
            }});
        region.setOnMouseDragged(new EventHandler<MouseEvent>() {
            @Override
            public void handle(MouseEvent event) {
                resizer.mouseDragged(event);
            }});
        region.setOnMouseMoved(new EventHandler<MouseEvent>() {
            @Override
            public void handle(MouseEvent event) {
                resizer.mouseOver(event);
            }});
        region.setOnMouseReleased(new EventHandler<MouseEvent>() {
            @Override
            public void handle(MouseEvent event) {
                resizer.mouseReleased(event);
            }});
    }

    protected void mouseReleased(MouseEvent event) {
        dragging = false;
        region.setCursor(Cursor.DEFAULT);
    }

    protected void mouseOver(MouseEvent event) {
        if(isInDraggableZone(event) || dragging) {
            region.setCursor(Cursor.S_RESIZE);
        }
        else {
            region.setCursor(Cursor.DEFAULT);
        }
    }

    protected boolean isInDraggableZone(MouseEvent event) {
        return event.getY() > (region.getHeight() - RESIZE_MARGIN);
    }

    protected void mouseDragged(MouseEvent event) {
        if(!dragging) {
            return;
        }
        
        double mousey = event.getY();
        
        double newHeight = region.getMinHeight() + (mousey - y);

        region.setMinHeight(newHeight);
        
        y = mousey;
    }

    protected void mousePressed(MouseEvent event) {
        
        // ignore clicks outside of the draggable margin
        if(!isInDraggableZone(event)) {
            return;
        }
        
        dragging = true;
        
        // make sure that the minimum height is set to the current height once,
        // setting a min height that is smaller than the current height will
        // have no effect
        if (!initMinHeight) {
            region.setMinHeight(region.getHeight());
            initMinHeight = true;
        }
        
        y = event.getY();
    }
}

Very very cool. I was about to try to write this... one search later, and here is perfectly working code.
Thanks!

Hello, I was attempting to combine this with the following: https://gist.github.com/miho/3821180 however the two don't seem to work together. Do you know of a way to create a draggable and resizable pane? I would like to provide a user experience where the user may open several independent panes and move and size them as they desire. Ideally it would be Sizable, Draggable and Scrollable for when the size is made smaller than the original Pane. Thanks!

Super nice DragResizer! I just make my stackpane FX node (, and all of its children FX nodes) perfectly resizable by add just one line: DragResizer.makeResizable(myStackpane);
Nice!

If anyone is interested, I made a little modification to the code in order to obtain both height and width resizing.

You can finde the code here: https://gist.github.com/cannibalsticky/a3057d6e9c1f029d99e6bc95f9b3340e

Happy coding!

is there any way to resize a decorated stage proportionally in square form ?

Cool! This is what I am looking for.

I found that transition will give better performance, so instead of

region.setMinHeight(newHeight);

one can use something like:

Timeline timeline = new Timeline(
    new KeyFrame(Duration.millis(1),
        new KeyValue(region.minHeightProperty(), newHeight, Interpolator.EASE_BOTH))
);
timeline.play()

Here is a version that allows diagonal (as well as horizontal and vertical) resizing. I use it with my PopWindow class which, when using an AnchorPane as a container, results in a window can be dragged to move as well as to resize. It also has a title bar with a maximize/unmaximize button and a close button. It is also compatible with JPro.