I have a feeling that the answer to this is going to make me feel really stupid, but here goes:
OK. I've built a 1st prototype that looks something like an old 5x7 Speed Graphic camera, except using the 7" Foundation display where the film would go.
All my first timelapse tests and some important info files were stored on the 32 gig SD card. They are on the desktop and in Pi Home.
This is all on a Pi2B, and it still is running Wheezy. Now I'd like to convert to Jessie if only for the ability to clone/backup the SD card.
My problem seems to be with the GUI not being signed in as Pi.
A 8gig PNY 'shortie' USB flashdrive when attached shows its contents in File Manager, so I assume it is mounted correctly. When I attempt to drag&drop files to the flashdrive, I get a Permission Denied.
Under File Properties (in GUI) there is a Permissions Tab, which reads Owner:Pi, Group:Pi, View Content: Anyone,Change Content:Only Owner, Access Content:Anyone.
So, in a sense this is a one time thing, and I could copy the files using Terminal. But for my camera purpose, I want to eliminate the keyboard if possible in the future (on Jessie).
I'm not finding navigation on the FOTS very easy, and there are odd problems such as File Manager's window being un-resizable and blocking the middle of the screen.
So I think what I need to know is how to register the GUI as 'Pi'; so I can drag&drop 'folders' to removable storage when the TL camera is in use.
However, I also have the feeling that I'm not seeing the problem clearly...