The problem
When building an input with layers, and then trying to use that input as a layer on a different input, only the original input is croppable and the layers themselves do not crop

Example
- Colour bars on Input 1, no layers
- Red colour on Input 2, with Layer 1 added on top
- Blank input on Input 3, with Layer 2 added on top
You can then manipulate the layer on Input 3 to move it around and resize it, which also resizes the layer. However when you crop, only the red colour is cropped and not the layer.

The proposed solution
Allow an input to be "flattened" via a toggle in its input settings, which then makes it act as a single input for use in layers on another input.

(Umless this is a bug, in which case can it be fixed?!)