I want to show checkboxes for selected tree nodes only but I am getting radiobuttons for every element in the tree

Here is my code

<?page title="MVVM Tree POC"?>
<zk>
    <borderlayout height="800px">
        <west size="25%"></west>
        <center>
            <window apply="org.zkoss.bind.BindComposer"
                viewModel="@id('vm') @init('com.nagarro.controller.TreeController')"
                title="Dynamic Tree" border="normal">
                <tree multiple="true" checkmark="true" rows="5"
                    model="@bind(vm.employeeTreeModel)">
                    <treecols>
                        <treecol label="First Name" align="center" />
                        <treecol label="Last Name" align="center" />
                        <treecol label="Age" align="center" />
                        <treecol label="Index" align="center" />
                    </treecols>
                    <template name="model" var="node" status="s">
                        <treeitem checkable="true">
                            <treerow style="text-align:center;">
                                <treecell
                                    label="@bind(node.data.firstName)" style="text-align:left;" />
                                <treecell
                                    label="@bind(node.data.lastName)" />
                                <treecell label="@bind(node.data.age)" />
                                <treecell label="@bind(s.index)" />
                            </treerow>

                        </treeitem>
                    </template>
                </tree>

            </window>
        </center>
    </borderlayout>
</zk>

I checked the zkoss reference for the multiple selection property and made the necessary changes in the above zul file. Still it doesnt show checkboxes. Instead it shows only radiobuttons.

Also, I want to show checkboxes in front of some selected tree nodes and not all of them.

Use

setMultiple(true)

on the model instance returned by vm.employeeTreeModel not the tree it self.

If you want just some to be checkable, change this

<treeitem checkable="true">

to something like that

<treeitem checkable="@load(node.checkable)">