Editing can orphan the ignore paths - please enhance UI

[dg1727]

First I will describe a UI problem I found, then suggested solutions.

For ease of explanation, I will mention how btrfs was involved with my finding the issue, even though the issue is in deja-dup.

1. /home is a btrfs partition
2. In Deja Dup, have a backup profile which backs up /home/username/ with an excluded (ignored) folder /home/username/test/
3. On Deja Dup's Folders tab, the excluded folder is shown relative to the included folder (/home/username/). That is, only the "test" part of the excluded folder path is shown. This hides the important fact that the excluded folder name is stored inside Deja Dup in absolute form.
4. With admin privileges, issue this command in a shell:
btrfs subvolume snapshot /home /home/snapshot
For the benefit of people who aren't familiar with the Btrfs filesystem: The given command makes a snapshot which includes all the pre-existing contents of /home. So the pre-existing test/ folder, for example, can be accessed as /home/snapshot/username/test/
5. On Deja Dup's Folders tab, in the left-hand pane ("Folders to back up"), remove /home/username/ and add /home/snapshot/username/
6. What a user will object to is that, if the backup is run now, /home/snapshot/username/test/ will be backed up, because the exclusion is still /home/username/test/ (which isn't within the backed-up folder /home/snapshot/username/) but the UI lets the user assume that the exclusion has been automatically updated to /home/snapshot/username/test/

Suggested improvements:
A. Show the ignore paths in absolute form. For paths that are subsidiary to folders that have ordinary-language aliases ("Home"), show the path as (Home)/test/ including the parentheses (rather than /home/username/test/)
B. Have an "Edit" button under each of the 2 panes in addition to the "Add" and "Remove" buttons. This would let the user inspect the absolute form of each path.
C. Detect when a change to either pane results in an ignored folder being not within any of the folders that are in the left-hand pane. If this happens, possibly show a dialog notifying the user of this, then change the color or icon of affected paths in the right-hand pane to indicate that they need to be edited.

I think that more than one of the above improvements should be made (not just B). Thanks for your time.

Ubuntu 12.04.1
deja-dup 22.0-0ubuntu2
duplicity 0.6.18-0ubuntu3
btrfs-tools 0.19+20120328-4

[Michael Terry (mterry)]

We show such home paths as ~/path/to/include/or/exclude now.