Playing multiple animations (Animation layering, runtime / tool support)

[Jeff Ward]

I see one of the benefits of using a bone based animation system to be that I should be able to create / control multiple animations that can be blended together at runtime (animation layering), but I'm not seeing any of the Spriter runtimes or the tooling support this. I saw some of the Sub Entity work, but what I'm asking for isn't quite that...

For example, if I created a seperate Left / Right running animation and a seperate forward / backward attack, I should be able to play any combination of run and attack together and have them blend (and hopefully look good....)

Another good example is having an aim "animation" that can be all of the proper aim positions from left to right, then programatically choose the point in time of that animation based on user input, pause that animation, and play other animations on top (run being the main example).  So now I can have a look similar to the game "Abuse" without a ton of extra effort

Is this possible in any of the provided implementations? Would it be possible to do this type of blending in my own implementation, and would the spriter format be... okay with it?