I use TeXworks editor on Windows where the default setting appears to be
a) Errors are underlined in red (but TeX code is not recognized and so it is underlined too; and ``comments'' are in red too) this makes for an egg hunt to find the errors.
b) You cannot permanently add a word to the dictionary
Can the default be changed and how do other editors perform in this respect?

Mit freundlichen Gr\"u\ss en:P – Andy May 25 '12 at 12:08