Adam,
I actually did what you said. I clicked on Add on spell checker window.But do you have any idea where will this be added? I need to do this in all the environments (QA, production etc.) so If I can add in my development version and just deploy the .dic file where ever required it will be nice.
How ever I am not ablt to find the added text (nbsp) in the en-US.dic file. Please advice.