The HUD, in many cases, causes issues reading or interacting with small inline PDFs. It should only be enabled for main frame PDFPlugins, matching the PDFView/SimplePDFPlugin behavior.
Created attachment 169272 [details] patch
See also: <rdar://problem/10269185>. I'm unsure if this is the best behavior in all, or even most cases.
(In reply to comment #2) > See also: <rdar://problem/10269185>. I'm unsure if this is the best behavior in all, or even most cases. Perhaps it should depend on the size of the plugin.
PDFKit handles not showing the HUD if it won't fit, and people seem to want subframe PDFs to have a HUD otherwise.