I use Acrobat to read schematic diagram PDFs output from Altium. One feature is that if you click on a component (such as a transistor) the PDF is designed such that a pop-up window comes up and displays data about that component, such as it's part number. The troublesome part is that you can't select and copy anything in the popup window. I don't know if that's an Adobe SW item or has something to do with how Altium designs its PDFs, but it would be WONDERFUL to be able to select and copy information from that pop-up.