Although less complete than PE/Elf formats, Bokken also have some PDF analysis capabilities that can aid in the study of this file format, and the GUI is modified accordingly to show the results of the analysis.
Mainly the difference between PE/Elf or standar GUI and the PDF one resides in the left panel. When working with this files the left panel shows a tree with the fundamental elemnts of the PDF analyzed, as described in this link.
As always doucle clicking on any of this elements will make the element to be highlighted on the hexdump at the right panel.
Bokken has one specific plugin for PDF files that pop ups a dialog with all the PDF streams found and the offset at wich they are located.