I don't have a fixed rule yet :/ Basically, the things that can be separated should move into a single file. The classes I've created in the file at first place should stay here as they are somewhat the "core" which are required to use the pdfListView, whereas the others are "nice to have". Just do what you think is the right thing - if I disagree, I will leave a comment and I don't think splitting code up in multiple file is a huge amount of work and something we should spend to much time on to come up with a rule that applies for all PRs. Okay?