I took a screen shot of the error i get if I use the squiggly and you can find it in the link above.
I followed the same steps for the spell checker using SpellingUI.enablespelling() and it worked sometimes and in one project, it gave the above error
1) But I do have SpelingUI and SpellingContextMenu
Haven't seen this myself but I saw this after some searching.
Someone mentioned in the thread that compiling for FP10 as a workaround, can you try that.