https://sourceforge.net/tracker/?func=detail&aid=3306717&group_id=152762&atid=785191

As illustrated in the following example, the first tree has some unexpected space between the scrollbar and the right border. It happens only if it coexists with another tree that is specified with vflex="true".

<zk>
<tree rows="5">
<treecols>
<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"/>
<treecell label="Item 2.2 is something who cares"/>
</treerow>
</treeitem>
</treechildren>
</treeitem>
<treeitem label="Item 3"/>
</treechildren>
</tree>
<tree vflex="true"/>
</zk>