Start file dialogs on the desktop

[kisaraki]

Summary

• start Open and first Save As operations on the user's desktop
• keep Save As beside an already named document
• retain explicitly supplied command-line directories and file parents
• use the cross-platform dirs provider instead of platform-specific APIs

Validation

• cargo test --all-features --all-targets on Windows and WSL/Ubuntu
• cargo clippy --workspace --all-features --all-targets -- --no-deps --deny warnings on Windows and WSL/Ubuntu

Contribution ownership

This contribution is entirely my own work. It is not created on behalf of, or connected with, any organization or company. I agree to contribute it under the repository's MIT License and to the repository's applicable contribution terms.

[stdmnpkg]

current behavior is consistent with DOS edit, vi, and GNU ed, and desktop is not always exist, no need to change.

[Leonard Hecker (lhecker)]

Is there a reason you picked the Desktop instead of e.g. the Documents directory?

On Windows at least, the default directory for the file picker is the last directory you navigated to for the given primary file type. E.g. if you last opened a .txt file in the Downloads folder, another application will start in the Downloads folder as well. That system is kind of clever.

For simplicity, I think the current CWD system is preferable.

[Leonard Hecker (lhecker)]

This project avoids dependencies intentionally.