Is the underlying LISP system technically unable to display documents at different zoom levels?
Usually the size at which documents are displayed have nothing to do with whether the displayed document is write-protected or not.
I strongly vouch for implementing a preference setting letting the user choose at what size a document is displayed in future versions (if technically possible).
My guess is that many older users of OPMO does not have the same eye-sight as they did when they were in their 20ies and could benefit from a a larger display size for documentation files.
I for one, find the tiny font size very taxing on the eyes. It's a bit more readable on the laptop screen but on a big desktop monitor where you sit farther away it's a pain (for me) to read.
Are there any plans to improve this in the future?