SelectEvents by trees with multiple selection do not correctly point out the selected items

<hlayout width="100%">
<tree id="tree" width="400px" rows="8" multiple="true" onSelect='_selection.setValue( "Selected items: " + event.getSelectedItems() );'>
	<treecols sizable="true">
		<treecol label="Name" />
		<treecol label="Description" />
	</treecols>
	<treechildren>
		<treeitem>
			<treerow>
				<treecell label="Item 1" />
				<treecell label="Item 1 description" />
			</treerow>
		</treeitem>
		<treeitem>
			<treerow>
				<treecell label="Item 2" />
				<treecell label="Item 2 description" />
			</treerow>
			<treechildren>
				<treeitem>
					<treerow>
						<treecell label="Item 2.1" />
					</treerow>
					<treechildren>
						<treeitem>
							<treerow>
								<treecell label="Item 2.1.1" />
							</treerow>
						</treeitem>
						<treeitem>
							<treerow>
								<treecell label="Item 2.1.2" />
							</treerow>
						</treeitem>
					</treechildren>
				</treeitem>
				<treeitem>
					<treerow>
						<treecell label="Item 2.2" />
					</treerow>
					<treechildren>
						<treeitem>
							<treerow>
								<treecell label="Item 2.2.1" />
							</treerow>
						</treeitem>
					</treechildren>
				</treeitem>
			</treechildren>
		</treeitem>
		<treeitem label="Item 3" />
	</treechildren>
</tree>
<label id="_selection" />
</hlayout>