Puzzled by "what's grayed-out and what's not" when using linked libraries (2.7)

I admit to being a little-bit confused with regards to “what’s grayed-out and what’s not” when using linked libraries these days. For instance:

  • If a mesh linked-in from a library has a shape key, but no armature (because it doesn’t need one), and a local proxy is made of that mesh … you can see that the shape-keys are defined but you can’t do anything with their influences in the Dope Sheet, action-editor or shape-key editor. I do not remember this being the case.
  • You can define actions, in the original library only, and you can add these to the NLA window. When you do this, it works: the shape-key is applied as the Action dictates. And you can scale these NLA strips to make them longer or shorter. But all of the input-boxes in the “N” panel are grayed-out and do not allow any input. (So, although you can use the mouse to set the scale of the strip, and see the change in the grayed-out boxes, you can’t enter any values into those boxes.)

Especially in the second case … “why not?” While it is understandable that the definition of an NLA strip should be protected, attributes such as Start Frame and End Frame pertain only to the placement of this strip within this animation. Intuitively, I would say that it’s a bug that I am not able to edit these values for an NLA-strip that references an action associated with a linked object.

Likewise, if the linked object defines shape-keys and I wish to animate the application of those keys through a proxy, I guess I don’t understand the rationale behind this being blocked.