fslint does not display the menu bar in 16.04, in either the top bar, if that is set, or the window bar, if that is set. It does not display the menu bar in 14.04 either. Works fine in 12.04. The package is fslint-gui. An apport bug report has been sent.
ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: fslint 2.44-2
ProcVersionSignature: Ubuntu 4.4.0-45.66-generic 4.4.21
Uname: Linux 4.4.0-45-generic x86_64
NonfreeKernelModules: nvidia_uvm nvidia_drm nvidia_modeset nvidia
ApportVersion: 2.20.1-0ubuntu2.1
Architecture: amd64
CurrentDesktop: Unity
Date: Sun Nov 13 15:55:05 2016
InstallationDate: Installed on 2016-11-06 (7 days ago)
InstallationMedia: Ubuntu 16.04.1 LTS "Xenial Xerus" - Release amd64 (20160719)
PackageArchitecture: all
SourcePackage: fslint
UpgradeStatus: No upgrade log present (probably fresh install)
I can confirm that 14.04 does not have a menu bar. Not sure if there ever was one, though. I certainly never needed it.