title: updating a shape in scene with a for loop using javafx
body: <p>Following is a code fragment. I am updating a rectangle using  a for loop when a button is pressed. This is a model for my ultimate intention of showing visualization of data model as it changes large number of times inside a for loop. It works but I see only one change. Now since I am changing the width randomly I should see large number of changes. It seems I am making a wrong assumption on something basic.</p>
  
  <p>The code goes below:</p>
  
  
  
  <pre>
   7 var rec: Rectangle = Rectangle {
  
   8             x: 10, y: 10
   9             width: 140, height: 90
  10             fill: Color.BLACK
  11         }
  12 
  13 Stage {
  
  14     title: &quot;MyApp&quot;
  15     scene: Scene {
  16         width: 200
  17         height: 200
  18         content: [
  
  19             rec,
  20             Button {
  21                 text: &quot;Button&quot;
  22                 action: function () {
  
  23                     for (i in [1..999]) {
  24                         rec.width = 25 + java.lang.Math.random()*50;
  25                     }
  26                 }
  
  27             }
  28         ]
  29     }
  30 }</pre>