This seems not possible.
But you could include with ui:include a shared snipped from webcontent in your dialog.xhtml viewToShow.xhtml e.g.:
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml"
xmlns:h="http://java.sun.com/jsf/html"
xmlns:p="http://primefaces.org/ui"
xmlns:ui="http://xmlns.jcp.org/jsf/facelets">
<h:head>
<title>My Dialog</title>
</h:head>
<h:body>
<ui:include src="/layouts/includes/footer.xhtml" />
</h:body>
</html>
