properties box does not list all choices to open TXT files

[Susan Cragin]

I have several TXT files and would like the option to open them with EMACS, which program I have compiled and installed myself.
The Properties box "Open With" tab shows lots of choices. Gedit is default, which is fine. "Recommended" contains other choices.
and then "Other Applications" which seems to show a random list of other applications.

Nowhere do I see EMACS (or EMACS 24). Nor do I see a chance to add it.

ProblemType: Bug
DistroRelease: Ubuntu 13.10
Package: unity 7.1.1+13.10.20131004-0ubuntu1
ProcVersionSignature: Ubuntu 3.11.0-12.18-generic 3.11.3
Uname: Linux 3.11.0-12-generic x86_64
ApportVersion: 2.12.5-0ubuntu1
Architecture: amd64
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
Date: Wed Oct 9 13:54:00 2013
InstallationDate: Installed on 2013-08-12 (58 days ago)
InstallationMedia: Ubuntu 13.10 "Saucy Salamander" - Alpha amd64 (20130811)
MarkForUpload: True
SourcePackage: unity
UpgradeStatus: No upgrade log present (probably fresh install)

[Sebastien Bacher (seb128)]

The programs need to provide a .desktop to be listed, if emacs doesn't have one that's a bug in that software