Primefaces contextmenu refresh when click on row of treetable - primefaces

Question

the situation is the following: I've got a treeTable with 3 different type of objects. The table contains the p:ajax with event="select". I wrote 3 different contextMenus, one for each type... and all works well.
My problem is that I want to enable/disable some of the menuItems; to do that I use the attribute "rendered" with condition based on properties of selected node.
All works, but only the second time I right-click on the same object (the first time the contextMenu isn't filtered).
Here is the code... (I'm including only one type of object for semplicity)
treeTable page:
<h:form id="form" prependId="false">
<p:treeTable value="#{documentsController.root}" var="document" id="docs"
selectionMode="single" selection="#{documentsController.selectedNode}">
<p:ajax event="select" process="#this" update=":form:menus"/>
<p:column headerText="#{msg['name']}">
<h:outputText value="#{document.name}" />
</p:column>
</p:treeTable>
<h:panelGroup id="menus">
<ui:include src="/menu/document_menu.xhtml"/>
</h:panelGroup>
<p:dialog id="document-rename-dialog" widgetVar="documentRenameDialog" header="#{msg.rename}">
<h:panelGrid id="doc-rename" columns="2">
<h:outputLabel for="name" value="#{msg.name}:" />
<h:inputText id="name" value="#{documentsController.name}"/>
</h:panelGrid>
<div class="spacer-10" />
<h:panelGroup layout="block">
<p:commandLink onclick="documentRenameDialog.hide();" value="#{msg.cancel}"/>
<p:commandLink actionListener="#{documentsController.renameDocument(documentsController.selectedNode.data)}"
process="#this :form:document-rename-dialog:doc-rename"
update=":form:docs"
oncomplete="documentRenameDialog.hide();"
value="#{msg.check}">
</h:panelGroup>
</common:dialog>
</h:form>
document_menu page:
<p:contextMenu id="contextMenuDocument" for="docs" nodeType="document">
<p:menuitem value="#{msg.rename}" process="#this docs" update=":form:document-rename-dialog:doc-rename"
actionListener="#{documentsController.setName(documentsController.selectedNode.data.name)}"
rendered="#{documentsController.canWrite}"
icon="ui-icon-pencil" oncomplete="documentRenameDialog.show();"/>
</p:contextMenu>
DocumentsController class:
#ManagedBean
#ViewScoped
public class DocumentsController {
private TreeNode root;
private TreeNode selectedNode;
private String name;
public TreeNode getSelectedNode() {
return selectedNode;
}
public void setSelectedNode(TreeNode selectedNode) {
this.selectedNode = selectedNode;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public void renameDocument(ArterDocument selectedDocument) {
if(name != null && !name.equals("")) {
System.out.println("Document renamed in: "+name);
((MyDocument)selectedNode.getData()).setName(name);
}
else
addErrorMessage("Error renaming document.");
}
public static boolean canWrite() {
if(((MyDocument)selectedNode.getData()).isWriteable())
return true;
return false;
}
}
The MyDocument class is a simple class with a String (name) and a boolean (writeable).
Can anyone tell me how I can show filtered contextMenu at first shot?
Thank you!