Apple II DeskTop allows the user to attempt to replace a file or folder with itself by dropping the file or folder onto the parent volume icon

[c0mmander8]

Describe the bug
Apple II DeskTop allows the user to attempt to replace a file or folder with itself by dropping the file or folder onto the parent volume icon, unlike the Mac and the IIGS.

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.
2. Double-click and open the "A2.Desktop" volume.
3. Drag the "Prodos" system file onto the "A2.Desktop" volume icon on the desktop.
4. A "Move..." dialog box appears stating, "That file already exists. Do you want to write over it?".
5. Click Yes.
6. An error message alert dialog box appears stating, "System Error".
7. Click OK.
8. The move is cancelled.

Expected behavior
Apple II DeskTop should not allow the user to attempt to replace a file or folder with itself by dropping the file or folder onto the parent volume icon and Apple II DeskTop should instead give an error message, just like the Mac and the IIGS.

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 #536, issue #630 and issue #631, this would be a good time to implement issue #449 and issue #450, if you decide to reconsider your position on those issues. "System error." really looks better than "System Error" and "I/O error." really looks better than "I/O Error.".

[c0mmander8]

The title of this issue and "Describe the bug" should instead read as follows:

Apple II DeskTop allows the user to attempt to replace a file or folder in the root directory of a volume with itself by dropping the file or folder onto the parent volume icon, unlike the Mac and the IIGS.

"Expected behavior" should instead read as follows:

Apple II DeskTop should not allow the user to attempt to replace a file or folder in the root directory of a volume with itself by dropping the file or folder onto the parent volume icon and Apple II DeskTop should instead do nothing at all, just like the Mac and the IIGS.