title: SWT composite - redraw problem
body: <p>I have a composite element, that initially has a Label. Now I call dispose on the it (the label) and create another label in the same container (composite elm), but I don't see the new text. It brings me to question how do I enable redraw on the composite, so that the new label (or any other component I might create) will render in place of the old one.
  Here is the code I have (separated into a unit test for redraw a composite)</p>
  
  <pre><code>private Label createLabel( Composite parent) {
      Label label = new Label(parent, SWT.NONE);
      label.setAlignment(SWT.CENTER);
      label.setLayoutData( new GridData( SWT.CENTER, SWT.CENTER, true, true) );
      return label;
  }
  
  private void changeText() {
      assert testCell != null : "Please initialize test cell";
      testCell.getChildren()[0].dispose();
      Label l = createLabel(testCell);
      l.setText("New TexT");
      testCell.redraw();
  }
  
  private void draw() {
      Display display = new Display();
      shell = new Shell(display);
      shell.setLayout(new GridLayout(2,false));
  
      testCell = new Composite(shell,SWT.BORDER);
      testCell.setLayout(new GridLayout());
      Label l = createLabel(testCell);
      l.setText("Old Text");
      Composite btnCell = new Composite(shell,SWT.NONE);
      btnCell.setLayout(new GridLayout());
      Button b = new Button(btnCell, SWT.PUSH);
      b.setText("Change");
      b.addListener(SWT.MouseDown, new Listener() {
          public void handleEvent(Event e) {
              changeText();
          }
      });
  </code></pre>
  
  <p>As you can see, I am calling redraw on the composite after I add a new element. Also, I have verified that after the call to dispose, testCell.getChildren().length returns 0, as expected, and when I create a new label, I get the same expression to return 1, verifying that the new element is indeed getting added to its parent composite container
  Am I missing something here ?</p>