Listener beforeshow on textfield

Good afternoun,

I have a question about dialog listeners.

I have this widget definition inside of my dialog:

     <vanity

            jcr:primaryType="cq:Widget"

            collapsed="{Boolean}true"

            collapsible="{Boolean}true"

            title="Vanity URL"

            xtype="dialogfieldset">

            <items jcr:primaryType="cq:WidgetCollection">

                <vanityPath

                    jcr:primaryType="cq:Widget"

                    cls="cq-propsdialog-vanityurl"

                    fieldLabel="Vanity URL"

                    xtype="textfield">

                    <listeners

                              jcr:primaryType="nt:unstructured"

                              loadcontent="function(field, record, path){VanityPath.loadPath(field);}"

                   beforeshow="function(field){VanityPath.loadPath(field)}"

                              beforestatesave="function(field, state){VanityPath.copyResult(field);}"/>

                </vanityPath>

                <vanityPathFinal

                    jcr:primaryType="cq:Widget"

                    name="./sling:vanityPath"

                    xtype="textfield"/>

                <vanityPathRedirect

                    jcr:primaryType="cq:Widget"

                    fieldLabel="Redirect Vanity URL"

                    name="./sling:redirect"

                    type="checkbox"

                    xtype="selection"/>

            </items>

        </vanity>

The beforeshow is not working and I cannot find what is the right definition.

Thank you for the help.