It's a difficult one this - TBH I can easily see both sides of the argument - on one hand she is just one girl with what is essentially a whim when you look at the surface of this but if she truly believes she should be covered head to toe for religous reasons then it is oppressive to make her do otherwise... OK it's not living in a war zone oppressive... It's not like she's trying to be 'trendy' either - if 80% of the school are muslim then as the only one to make an issue out of this she is probably shunned by the majority of the other muslim kids too... It's VERY easy to imagine that all of this is coming from her parents as well but I think that's what Rave was alluding to - shoving any belief down your kids throat really isn't helping anyone - I'm not saying all religon is bad but it's very easy to give bad examples
Then there's the general social issue - which I think is where most people worry - I personally don't like either extreme - that any community and their values can be disregarded or allowed to dictate simply because the government is too afraid of seeming racist / weak / whatever...