Do you mean, after you have posted the comment. I am forever pressing send and then when the post comes up, the spelling shieks at me!
Ok so I posted the first bit.... then I pressed edit..... the edit option comes along the bottom of the post. My comment comes up in the message box. I've typed the extra or corrected the mistakes and then I am going to press save.....
Back to the editing..... I managed to save this so I'm not sure what you are doing differently.
Perhaps you could try editing your original post like this.....