Hmm, ah, so the main purpose for single line matching is to save memory, since a 1-2 GB txt file might cause some serious trouble.. and is just not as optimized as searching line by line, no?
But again especially regex like "(.+)\nfoobar" or anything with "\n" will fail without multi-line search. Anyway, I see why there are both options. But at least there should be something like a warning that "\n cannot be found in single-line mode" or something, unless someone has a better solution, which could also be optimized while being able to detect every symbol and regex correctly (one less option to care about).