2.x platform

Major upgrade to GTK (3 years in development)
Taken as an opportunity to fix many of the problems in the interface that could not be fixed without breaking compatibility.
Harder guarantees of binary compatibility
Within a minor series (2.0.x, 2.2.x, etc), forward and backward binary compatibility is maintained
Has required us to develop new ways to introduce APIs
adding a bad API may mean managing that API for years
libegg is part of the new development process