Find out if Flex component (tree) ist scrollable?

How can you find out if a Flex Component (in my case the tree) is scrollable? I tried it like this

if (_listOwner.height < _listOwner.measuredHeight) {
  // so stu开发者_StackOverflow社区ff
}

from within the tree's item renderer but didn't succeed. Access to the tree's scrollbar is private so that I can't get the info that way.

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Found a solution by extending the tree class:

public class ExtendedTree extends Tree
{
    public function ExtendedTree()
    {
        super();
    }

    public function get isVerticalScrollable():Boolean
    {
        if (super.verticalScrollBar == null || super.verticalScrollBar.visible == false)
            return false;
        return true;
    }
}

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Use the maxVerticalScrollPosition and maxHorizontalScrollPosition properties.