ZCML File
configure.zcml

<configure
    xmlns="http://namespaces.zope.org/zope"
    i18n_domain="zope"
    >
<adapter
    factory=".form.default_page_template"
    name="default"
    />
<adapter
    factory=".form.default_subpage_template"
    name="default"
    />
<adapter
    factory=".form.render_submit_button"
    name="render"
    />
<adapter
    factory=".namedtemplate.NamedTemplatePathAdapter"
    for="*"
    name="template"
    />
<adapter
    factory=".errors.InvalidErrorView"
    permission="zope.Public"
    />
<class
    class=".form.Widgets"
    >
<allow
    interface=".interfaces.IWidgets"
    />
</class>
<class
    class=".form.Actions"
    >
<allow
    interface=".interfaces.IActions"
    />
</class>
<class
    class=".form.Action"
    >
<allow
    interface=".interfaces.IAction"
    />
</class>
</configure>