How to create dynamically Resizable shapes in java

I have three problems:

I want to create resizable shapes with box bounding...
I also want to know how to get child seleted in a Pane.
I'm creating multiple shapes on a pane. I want to change some property of that shape say Fill.. How do i do it??

Thanx

Next example will answer your questions:

for (1) it uses binding, connecting pane size with rectangle size
for (2) it adds setOnMouseClick for each rectangle which stores clicked one in the lastOne field.

for (3) see code of setOnMouseClick() handler

public class RectangleGrid extends Application {

  private Rectangle lastOne;

  public void start(Stage stage) throws Exception {
    Pane root = new Pane();

    int grid_x = 7; //number of rows
    int grid_y = 7; //number of columns

    // this binding will find out which parameter is smaller: height or width
    NumberBinding rectsAreaSize = Bindings.min(root.heightProperty(), root.widthProperty());

    for (int x = 0; x < grid_x; x++) {
        for (int y = 0; y < grid_y; y++) {
            Rectangle rectangle = new Rectangle();
            rectangle.setStroke(Color.WHITE);

            rectangle.setOnMouseClicked(new EventHandler<MouseEvent>() {
                @Override
                public void handle(MouseEvent t) {
                    if (lastOne != null) {
                        lastOne.setFill(Color.BLACK);
                    }
                    // remembering clicks
                    lastOne = (Rectangle) t.getSource();
                    // updating fill
                    lastOne.setFill(Color.RED);
                }
            });

            // here we position rects (this depends on pane size as well)
            rectangle.xProperty().bind(rectsAreaSize.multiply(x).divide(grid_x));
            rectangle.yProperty().bind(rectsAreaSize.multiply(y).divide(grid_y));

            // here we bind rectangle size to pane size 
            rectangle.heightProperty().bind(rectsAreaSize.divide(grid_x));
            rectangle.widthProperty().bind(rectangle.heightProperty());

            root.getChildren().add(rectangle);
        }
    }

    stage.setScene(new Scene(root, 500, 500));
    stage.show();
  }

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