Continuum is described as "a light-weight native OS X IDE for Mono".
It is hosted at https://github.com/jesse99/Continuum as an open source project. Written by Jesse Jones.
There is no specific Cobra support at this point, but Continuum has a pluggable architecture and it's open source, so it should certainly be possible.
You can open the app preferences panel, select language globs from the left, and use the + button to add a *.cobra glob with the text language (or something close to Cobra syntax to get some highlighting, such as Python).
You can also add a custom language if you're comfortable with regexen by pressing the Open Languages button there. Let's say you copy Python.xml from "standard" to "user", renaming it to "Cobra.xml". The full path will then be:
If launched from the command line, Continuum may say:
WARNING: The locate database (/var/db/locate.database) does not exist. To create the database, run the following command: sudo launchctl load -w /System/Library/LaunchDaemons/com.apple.locate.plist Please be aware that the database can take some time to generate; once the database has been created, this message will no longer appear.
You don't have to create the "locate" database, but Continuum's "open selection" won't be able to find files and right-clicking on types won't let you open the associated file.
As of 2010-07, the Continuum launch script inside the app needs write access to the app directory. So if you have trouble launching, make the app directory writeable and try again.