failed to find an app to open a .chm file

I double-clicked a .chm file (compiled help) in Nautilus
sessioninstaller pops up saying no installed app can handle the file
I ask it to search one for me

what happen:
- no app is found
- a dialog tells me to confirm installing the software (even when there's nothing to install and Install option is disabled)

what I expected to happen:
- apps should have been found. There's two apps in the main repo: xCHM and fbReader (i tried xCHM and works fine)
- I should have been able to install one of those and open the file
- if there where really no app to handle the file, no "Install software?" dialog should show, just a notice.

Using Ubuntu 12.04.01
sessioninstaller: Instalados: 0.20+bzr128-0ubuntu1.2

I confirmed this on Ubuntu 12.10 as well. Not sure if it's an sessioninstaller bug or if it depends on some xCHM package metadata to work.

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: sessioninstaller 0.20+bzr128-0ubuntu1.2
ProcVersionSignature: Ubuntu 3.2.0-32.51-generic 3.2.30
Uname: Linux 3.2.0-32-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 2.0.1-0ubuntu14
Architecture: amd64
Date: Fri Nov 2 21:41:45 2012
ExecutablePath: /usr/bin/session-installer
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Release amd64 (20120425)
InterpreterPath: /usr/bin/python2.7
PackageArchitecture: all
SourcePackage: sessioninstaller
UpgradeStatus: No upgrade log present (probably fresh install)