Original source: http://www.zkoss.org/forum/listComment/17412-borderlayout-not-working-on-5-0-8-version

Airton says this fragment is not displayed properly:

<?page title="border layout" contentType="text/html;charset=UTF-8"?>
<zk>
<window title="border layout" border="normal">
<borderlayout height="300px">
<north>
<borderlayout height="120px">
<center>CENTER</center>
</borderlayout>
</north>
</borderlayout>
</window>
</zk>

Cvarona, on the other side, complains about this page not being displayed at all in the online zksandbox (although it does when loaded as a standalone zul page):

<window width='100%' height='100%'>
<borderlayout >
<north maxsize="40" collapsible="true" style="background: teal;" border="none">
<hbox style="background: teal; color: white; margin: 15px;">
<label style="padding:20px; color: white; font-size: 150%" />
</hbox>
</north>
<west minsize="150" size="20%" flex="true" splittable="true" collapsible="true" border="none">
<tree multiple="false" height="100%" width="100%">
<treecols>
<treecol label="Some label"/>
</treecols>
<treechildren>
<treeitem label="Some label" >
<treechildren>
<treeitem label="Some label" />
</treechildren>
</treeitem>
<treeitem label="Some label" >
<treechildren>
<treeitem label="Some label" />
</treechildren>
</treeitem>
<treeitem label="Some label" >
<treechildren>
<treeitem label="Some label" />
</treechildren>
</treeitem>
<treeitem label="Some label" >
<treechildren>
<treeitem label="Some label" />
</treechildren>
</treeitem>
<treeitem label="Some label" >
<treechildren>
<treeitem label="Some label" />
</treechildren>
</treeitem>
</treechildren>
</tree>
</west>
<center flex="true" autoscroll="true" border="none">
<borderlayout width="100%" height="100%">
<center flex="true" border="normal">
<tabbox width="100%" height="100%" sclass="lite">
<tabs />
<tabpanels />
</tabbox>
</center>
<west minsize="200" size="20%" splittable="true" collapsible="true" border="normal" autoscroll="true" style="background-color: #86a4be;">
<vbox>
<vlayout visible="false"></vlayout>
</vbox>
</west>
<north border="normal" style="background-color: #86a4be;">
<vbox height="95px" spacing="0px">
<menubar width="100%">
<menu label="Some label">
<menupopup>
<menu label="Some label">
<menupopup>
<menuitem label="Some label" />
</menupopup>
</menu>
<menu label="Some label">
<menupopup>
<menuitem label="Some label" />
</menupopup>
</menu>
<menu label="Some label">
<menupopup>
<menuitem label="Some label" />
</menupopup>
</menu>
<menu label="Some label">
<menupopup>
<menuitem label="Some label" />
</menupopup>
</menu>
<menuitem label="Some label" />
</menupopup>
</menu>
</menubar>
</vbox>
</north>
</borderlayout>
</center>
</borderlayout>
</window>

There is another test case; the corresponding sample zul is the same as above, but removing the enclosing window. When loaded via Executions.createComponentsDirectly specifying the window _awindow:

<borderlayout id="_layout">
<west>
<tree>
<treecols>
<treecol label="Some label"/>
</treecols>
<treechildren>
<treeitem label="Another label">
<treechildren>
<treeitem label="Yet another label" onClick="Executions.createComponentsDirectly( [reader], "zul", _awindow, null );" />
</treechildren>
</treeitem>
</treechildren>
</tree>
</west>
<center>
<window id="_awindow" />
</center>
</borderlayout>

it does not get displayed in ff5.0 (it does in ie9), although the html gets generated. Strangely enough,it suffices to active firebug in order to make it appear.

None of the above happend in zk5.0.7.1