ZCML File
configure.zcml

<configure
    xmlns="http://namespaces.zope.org/zope"
    xmlns:browser="http://namespaces.zope.org/browser"
    >
<include
    package=".toolbar"
    />
<include
    package=".xmltree"
    />
<include
    package=".addinginfo"
    />
</configure>