Information visualisation benefits from the Semantic Web: multimodal mobile interfaces to the Semantic Web offer access to complex knowledge and information structures. Natural language dialogue systems are ideal interfaces to personal digital assistants (PDAs) or other handheld clients. We explore more fine-grained co-ordination of multimodal presentations as answers to natural language questions about a specific domain by graph-based visualisation and navigation in ontological RDF result structures. Semantic Navigation on mobile devices leverages graphical user interface activity for dialogical interaction in mobile environments. Constraint-based programming helps to find optimised multimedia graph visualisations.