Nice choice of license. MPL. Much clearer and straightforward than LGPL. Existing files and changes to them must stay MPL licensed. New files can be any other license.
LGPL is pretty clear, it's just not very convenient. It's only unclear when your start going through mental hoops to make it seem more laisser-faire than it is.
For instance, it's just about impossible to distribute an iOS application in a kosher way.
I only recently learned about the MPL and I'm a fan. It seems to be a really nice alternative to GPLv3 and LGPL and offers a lot of convenience while still being copyleft.
