The width values from the widths PDF property should be taken with priority compared to the font file calculations. Fix available in R2 2018 SP1 release version.
This is Unicode (UTF-16BE) encoding for the Adobe-GB1 character collection; contains mappings for all characters in the GB18030-2000 character set. Described on page 443 in Pdf Reference 1.7.
This might result in invisible annotations.
Use the attached project to reproduce.
Workaround:
var combo = toolbar.ChildrenOfType<PercentComboBox>().FirstOrDefault();
When importing a document containing Outlines (Bookmarks) containing Actions with an empty dictionary:
<</Title(Bookmarks)/Parent .../First .../Last .../Prev .../A<<>>/Count ...>
leads to an exception thrown: System.MissingMethodException: 'Cannot create an abstract class.'