title: why letter 'f' oftentimes cannot be copied from text in pdf files?
body: <p>I am not sure if this question qualifies here, but it seems odd to me letter 'f' often get messed up when copied from pdf text.</p>
  
  <p>I do research as a student, and I read a lot of papers. This happens a lot when I want to copy the name of a paper to rename the pdf file.</p>
  
  <p>For example, I opened the link <a href="https://ccse.lbl.gov/Publications/donev/HybridLLNS.pdf">a paper</a> from built-in pdf display plug-in of Chrome on a Macbook Pro with OSX 10.9. Try copy the title of the paper and paste it. The 'f' in 'fluids' will be missing.</p>