In Omnigraffle, if I want to export a fitted PDF that only encloses the objects I've drawn, I can select "export all objects" from the export menu.
However, I don't know what to do if I have a multi-canvas document in omnigraffle and I want to export a PDF of the entire document with each canvas sized appropriately. If I export the entire document it exports the entire canvas.
Now I could manually resize each canvas, but that's a pain if I later wish to add something that changes the canvas size. I'd much prefer an automatic solution if one exists.