I want to use cycle layers and the walk behavior at the same time. But I can't set a keyboard trigger to the arrow key, and I can't set the walk behavior to other keys than the left and right arrow keys.
One of the things that I want to achieve is letting the hands open and close while running to give the character some extra expression.
Yes, currently (and this might get changed down the road) arrows can only be used for Walk.
If the character has multiple views, I guess you could have cycle layers set to start immediately instead of triggered and do the math to figure out when/where the open handed frames will need to be. Or you could make the whole arms cycle layers instead of the pre-determined Walk behavior ones. Either way multiple views seems like the way to go, because those get triggered when you press the arrow keys already, so anything inside them will get triggered too (and hidden in the default non-profile view).