I'm new to this format and came from CAD which can be dynamically resized
manually or programmatically so yes, I'm concerned with proportionality
because its my understanding that the slides are static in this context,
i.e. can be resized at design-time but are static at run-time. Its really
going to become a matter of learning what software is used to play back the
slide(s), what software can be used for playback and whether for example
they are embedded in a Silverlight application and so on.