When running with xfwm4, pdfpc-4.0.0 thinks that the primary screen is larger than its physical size. See the following upstream bug reports for details: https://github.com/pdfpc/pdfpc/issues/68 https://github.com/pdfpc/pdfpc/issues/71 This makes version 4.0.0 practically unusable. I don't see the problem with pdfpc-3.1.1.
Please test 4.0.1, I added it to the tree
Please test 4.0.1
Sorry for the delay, I couldn't test because of hardware issues. Version 4.0.1 has fixed the problem here.