I would like the option to open PDF file attachments in the default PDF editor on my windows desktop. Then I could mark up PDF attachments with the editor I choose, and hopefully be able to save it back in the exact same location without any extra clicks. Ideally it should create a new version with every save. This would be very helpful when collaborating with clients and allow them to mark it up with whatever they choose to use to edit. This also needs to be in conjunction with embedding the PDF in the Activity Pane so that one can scroll back over the history of the project and see how it progressed and why. Example: I create a drawing of a kitchen, a client can comment on the drawing or mark it up with notes, lines, annotations of any sort. Then I update the drawing to his/her requests and insert the new PDF for him/her to view and either approve or mark up again. Next I want to do a site measure, and again mark up my PDF with any measurement changes. At any given time during installation or prior, anyone I give access should be able to access these revisions and comments to see why the end result is how it ended up. I do not want to have to open each attachment individually to find the attachment that shows the information I am searching for.