@HyperspaceMadness is the code master but from what he has told me, it takes an awful lot of jumping around and editing to put anything like a simple on/off switch in the RA interface.
A lot of the parameters have multiple settings that you have control over. Exactly what kind of control are you looking for? There is a mile long list of parameters in the parameters dialog, only the images require manual editing of the *.slangp.
HSM and I have talked about multi-page parameter lists, to shorten the list, but I don’t think a solution has been found yet. With HSM’s stubborn and generous nature, all things are possible, given enough time.
The cool thing about doing things inside the shader is that you can see, in real time, the effect it has. Changes to things like scaling, blending mode, and layer depth, can all be seen while you are making the changes.
Alternatively, when you are using an overlay and want to adjust the view port size, the overlay disappears when you call up the RA UI. (Since the overlay and the menu are both “On Screen Overlays”.)