I confirm that is just the spell checker.
Mike and myself are discussing since some time about the possibility to check the code in the javascript before save to the module. I already did something in that sense but I was not happy of the result so, for the moment, I put the priority on the basic itself.
The idea behind all that, is the possibility to "precheck" the code and possibly tokenize it in order to simplify and speedup the basic.
So, "basically", we should be able to highlight errors, check labels cross references, syntax errors, ...
I agree with Mike's point of view where all can/must be done in the browser, without any external tool.
To be continued .....