As the title says, I decided to have a look at the HDR Shortcut plugin (https://codeload.github.com/Nikos-Prinios/HDRI-lighting-Shortcut/zip/master) and so installed in Blender (2.78a). I already had my own Shadow Catcher plugin (https://github.com/RokenPrice/Shadow-Catcher).
Now, my latest version of the shadow catcher includes a shadow blur option in the toolshelf on the compositing window which driver X & Y blur in a compositing node. The HDRI plugin also has a blur option in the interface in the world settings. With both enabled, my compositing option doesn’t drive my node, but instead drives the node on the HDRI plugin. If I disable the HDRI plugin it works properly as expected.
Now, I don’t know enough about the way Blender scripts interact with each other. I tried renaming mine in the script but to no avail.
Does anyone know what I need to do to isolate my controls from the HDRI control?