Here's what works:
* Scene Open/Close
* Render / pause / stop
* Image save as...
* Tonemapping sliders, incl reinhard, camera and linear
* Layer lights adjustment
That's all the features for now - so slightly less than you can do in the existing windows gui - but if there aren't too many issues in stomping out bugs then I'll be keen to get your feedback on features that would be good in the gui.
Thanks for being so patient. Talk soon.
