[ChelpanovIlya]

Proposed changes

When multiple mc instances are running, clipboard_store and clipboard_paste settings in the ini file get reset to empty strings.

Steps to reproduce:

1. Set clipboard_store and clipboard_paste in ~/.config/mc/ini
2. Open multiple mc instances in different terminals
3. Close one mc instance — it saves the config with the correct values
4. Close another mc instance that was started before the config was edited — it reads the OLD ini (before edits were made), loads empty strings for clipboard_store/clipboard_paste, and overwrites the config, erasing the user's settings

The root cause is that save_setup() unconditionally writes clipboard_store_path and clipboard_paste_path to the ini file, even when they are empty strings (which is the default when no clipboard utility is configured through mc's UI). This means any mc instance that started before the user edited the ini will overwrite the settings with empty values when it exits.

Fix: only write clipboard_store and clipboard_paste to the ini when the values are non-empty, preserving user-configured values.

Checklist

• I have referenced the issue(s) resolved by this PR (if any)
• I have signed-off my contribution with git commit --amend -s
• Lint and unit tests pass locally with my changes (make indent && make check)
• I have added tests that prove my fix is effective or that my feature works
• I have added the necessary documentation (if appropriate)

[ossilator]

huh? i would have expected this to be an obvious reject: it's just the way mc's config works. adding exceptions for particular options is confusing, and just bad practice.

a proper generic solution would do a 3-way merge. that would require saving the originally read values (or at least tagging modified ones), and re-reading the file prior to writing it (at least if its timestamp changed). that's what proper frameworks like kde's kconfig do. glib has gsettings, but that's in gio, so i suppose mc isn't going to use it.