At the public high school I attended in France our history teacher did cover the slave trade in quite some detail but mostly as a British/US phenomenon (ironic since we where in Bordeaux which was one of the big French ports active in the slave trade). As for colonial history I know we covered the early Spanish and Dutch colonial empires but not much of more recent colonial history. The sense was that the more recent history was too controversial and would not make it onto our final Baccalaureate exam so it wasn't a priority.