When I create a string property for the object type, I can modify that property in the active object. But when I create another string property for the f-curve type, it said it is read-only.
The script:
import bpy
bpy.types.Object.objprop = bpy.props.StringProperty(name = "objString")
bpy.context.object.objprop = "mod_objString"
bpy.types.FCurve.fprop = bpy.props.StringProperty(name = "fString")
bpy.context.object.animation_data.action.fcurves[0].fprop = "mod_fString" # error occured on this line
error:
some testing in the built in python interpreter:
Edit: The blend file (although it is almost empty but just in case):