Override getChildren() in ScalableRootFigure of PopUpHelper

This is a follow-up to 4b38172, where
a custom RootFigure class was created, which injects a
ScalableLayeredPane between itself and its content.

The add() method was already overridden to add any additional children
to the scalable figure. One also needs to override the getChildren()
method to delegate to the same figure.

Author: ptziegler

org.eclipse.draw2d/src/org/eclipse/draw2d/PopUpHelper.java

@@ -12,6 +12,8 @@
  *******************************************************************************/
 package org.eclipse.draw2d;
 
+import java.util.List;
+
 import org.eclipse.swt.SWT;
 import org.eclipse.swt.graphics.Color;
 import org.eclipse.swt.graphics.Rectangle;
@@ -265,6 +267,11 @@ public void add(IFigure figure, Object constraint, int index) {
 				scalablePane.add(figure, constraint, index);
 			}
 
+			@Override
+			public List<? extends IFigure> getChildren() {
+				return scalablePane.getChildren();
+			}
+
 			@Override
 			public double getScale() {
 				return scalablePane.getScale();