Scratch

In my "skeleton poser" project, it took a lot of work (and math) to make the body parts attach to each other.  And the result is not ideal - it's hard to edit the attach points and there's a lag between when the body is dragged or animated and when the attached limbs are updated.

I would like to propose a new "attach to sprite" block.  This block would anchor the current sprite to a specified sprite at the current sprite's location.  Once attached, the sprite's x,y, and direction would become relative to the attached-to sprite.  There should obviously be a "detach" block as well.

With this new block, you could create all kinds of hierarchical animation:
  - you could attach spinning wheels to a car that automatically move with the car
  - you could attach eyes and mouth to a face
  - you could make a moon that orbits a planet which orbits a star
  - you could implement a platform game where a character can jump onto a moving platform and then move with it
  - and so on...

Note: attachment just means the attached sprite's location is now in the local coordinate system of the parent sprite.  This shouldn't prevent the attached sprite from being moved or dragged; it should just move relative to the parent.  For instance, if you jiggle y up and down on a car tire, it should move up and down relative to the car (like a car suspension) even if the car is rotated as if climbing a hill.

Oh, and if you change the size of the parent sprite, the coordinate system should scale to preserve the attachment, and the attached sprites should scale too.  E.g. if you scale the car, the wheels should scale.