In reply to Fredt:
Hello,
I'm currently in Bangkok ad I'd say it's fine, I got here on the 9th of December and for 10 days was staying right in the middle of all the protests, walked through the dead centre of them on a daily basis and some times more than once a day. No problems what so ever or even a hint that there would be one, their peaceful protests actually seem to me peaceful rather than those back home which may or may not be.
As someone else already mentioned here it's a good idea to keep away from the protests as a general rule of thumb but I haven't and won't be making any effort in the future to do so here as it seems fine to me.
Two things to take note of though, firstly if she's staying around the Khao San road area getting a taxi to her accommodation could be tricky due to road closures, which roads are closed and which are open keeps changing. This can cause a problem generally with transport but I just walked everywhere which I prefer anyway, only wanted to use taxis to meet friends who weren't close by to where I was.
Secondly there is a scam running where someone will walk up to here, tell her it's dangerous for tourists due to the protests (it's really not) and get her to take a cheap 'government' tuk tuk (there's no such thing) which will take here to shops and such where they'll charge her to much for stuff. This scam has been around for ages but I think because they're saying the protests are dangerous more people are falling for it (I've spoke to a few who have). Although at worst if you call for this scam you lose time & money but at best if you don't buy anything you lose time.
If you want to know any thing else feel free to send me a message, will be in Bangkok for a few more days.