When a volume shortcut of a non-startup disk volume is chosen to be edited in Edit a Shortcut..., the contents of Edit a Shortcut... is that of the startup disk instead of that of the non-startup disk volume

[c0mmander8]

Describe the bug
When a volume shortcut of a non-startup disk volume, not a shortcut of a file or a folder located on a non-startup-disk volume, is chosen to be edited in the Shortcuts > Edit a Shortcut... file picker dialog box, the contents of the Shortcuts > Edit a Shortcut... file picker dialog box is that of the startup disk instead of that of the non-startup disk volume. This means that the "Disk: /" line of text above the file picker states "Disk: /" plus the name of the startup disk instead of stating "Disk: /" plus the name of the non-startup disk volume, the contents of the file picker is that of the startup disk instead of that of the non-startup disk volume and the "Enter the full pathname of the file:" text field states "/" plus the name of the startup disk instead of stating "/" plus the name of the non-startup disk volume.

To Reproduce
Steps to reproduce the behavior:

1. Start Apple II DeskTop from "A2.Desktop", which is a fresh copy of the "A2DeskTop-1.2-alpha40-en_800k.2mg" disk image, with a fresh copy of "Live.Install" mounted, which is a fresh copy of the "Live.Install.po" disk image from ftp://ftp.apple.asimov.net/pub/apple_II/images/gs/os/gsos/Apple_IIGS_System_6.0.4/.
2. Click on the Shortcuts menu and go to Shortcuts > Add a Shortcut....
3. Click on the "Change Drive" button until the "Disk: /" line of text above the file picker states "Disk: /Live.Install".
4. Click OK without first choosing a file or a folder from the file picker or first typing in the file path of a file or a folder in the "Enter the full pathname of the file:" text field.
5. Click OK again without first changing the default name of the shortcut.
6. Click on the Shortcuts menu and go to Shortcuts > Edit a Shortcut....
7. Select the shortcut named "Live.Install" you have just created in steps 2-5.
8. Click OK.
9. The contents of the Shortcuts > Edit a Shortcut... file picker dialog box is that of "A2.Desktop" instead of that of "Live.Install". This means that:
10. The "Disk: /" line of text above the file picker states "Disk: /A2.Desktop" instead of stating "Disk: /Live.Install".
11. The contents of the file picker is that of "A2.Desktop" instead of that of "Live.Install".
12. The "Enter the full pathname of the file:" text field states "/A2.Desktop" instead of stating "/Live.Install".

Expected behavior
When a volume shortcut of a non-startup disk volume, not a shortcut of a file or a folder located on a non-startup-disk volume, is chosen to be edited in the Shortcuts > Edit a Shortcut... file picker dialog box, the contents of the Shortcuts > Edit a Shortcut... file picker dialog box should be that of the non-startup disk volume instead of that of the startup disk. This means that the "Disk: /" line of text above the file picker should state "Disk: /" plus the name of the non-startup disk volume instead of stating "Disk: /" plus the name of the startup disk, the contents of the file picker should be that of the non-startup disk volume instead of that of the startup disk and the "Enter the full pathname of the file:" text field should state "/" plus the name of the non-startup disk volume instead of stating "/" plus the name of the startup disk.

Screenshots
I am sorry. I have no screenshots to help explain my problem.

System Details (please complete the following information):

• System [e.g. Apple IIe Enhanced, Apple IIc, Apple IIgs] Apple IIGS (ROM 01)
• Emulator? [e.g. real hardware, or emulator name] GSplus 0.14 (the latest version of the program)
• ProDOS version ProDOS 2.4.2 (the latest version)
• DeskTop version (from About > Apple II DeskTop...) Apple II DeskTop 1.2 Alpha 40 (the latest version of the program)
• Other [e.g. mouse, memory expansions, disk types, etc]

Additional context
As referenced in issue #612, please do not ban me for my long issue title for this issue. I am trying to be helpful. I find it extremely hard to shorten my long issue titles. Could you please shorten my long issue title for this issue for me after I post this issue?