Various improvements (blending documentation, AvoidNavigationCollisions fix, buttonXx

[DP News-Robot]

I’m happy to be swamped with things to announce about the engine! ? So, after previous announcements this weekend, one more list of new stuff ? We have an extensive documentation how blending (partial-transparency) works. While the engine tries its best, it’s not always possible to make blending automatically “just work”. This documentation should help …