Nautilus allows to rename any generic file, including the extension part. For example, I can rename "Image.jpeg" to "Image.jpg" or even "Image.png" which is not right, but still possible.
Dekstop files are different. If I try to rename firefox.desktop to firefox.txt in order to edit this file manually, I can't do so, because nautilus always add desktop extension. If I accidentially rename regular file to a desktop file, I can't rename it back, because Nautilus throw an error, that this desktop file has a wrong format (obviously because it is not a desktop file).
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ProblemType: Bug
ApportVersion: 2.20.9-0ubuntu7.3
Architecture: amd64
CurrentDesktop: pop:GNOME
DistroRelease: Pop!_OS 18.04
InstallationDate: Installed on 2018-01-08 (213 days ago)
InstallationMedia: Pop_OS 17.10 "Artful Aardvark" - Release amd64 (20171219)
Package: nautilus 1:3.26.3-0ubuntu4 [origin: Ubuntu]
PackageArchitecture: amd64
Tags: third-party-packages wayland-session bionic
Uname: Linux 4.18.0-041800rc8-generic x86_64
UnreportableReason: Этот пакет не является официальным пакетом Pop!_OS. Пожалуйста, удалите все сторонние пакеты и попробуйте снова.
UpgradeStatus: Upgraded to bionic on 2018-05-04 (97 days ago)
UserGroups: adm kvm lpadmin sudo tty vboxusers video
_MarkForUpload: True
usr_lib_nautilus:
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apport-collect 1786233
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