Passing special character file names to external programs fails

For example, if I select testüng.ini in a FilePath, then preview it, then context-click on "open in external editor" I get the following error due to character encodings:

gio: file:///home/mir/Desktop/test%25C3%25BCng.ini: Error when getting information for file “/home/mir/Desktop/test%C3%BCng.ini”: No such file or directory

See https://doc.qt.io/qt-5/qurl.html#ComponentFormattingOption-enum