[BUG]: appended files are not encrypted.

[stdStudent]

When adding new files to an encrypted archive, the newly added files are not being encrypted. It doesn't seem to be an issue with particular compression algorithm or archiving format...

Steps to reproduce:

1. Create a password-encrypted archive.
2. Drag'n'drop new file to the archive.

The resulting file is not encrypred.

If I try to add a file via "Add" button, it says "The operation is not supported for this folder."

If I'm doing something wrong, please, tell me how to properly append a file to an encrypted archive.