Is it possible to have those elements (camera, environment, film settings, animation, kernel, render layers, render passes, imager, post processing) horizontally, as small buttons?
This would not be a simple to implement as you might think - since some of the rendertarget pins are optional (ie. the Visible Environment), and others allow different types of nodes (for example, there are 4 different type of kernel nodes - so changing the kernel type has to be done at the rendertarget pin level rather than the kernel pins).
An option that might work would be to have the camera, kernel, environment, etc buttons above the rendertarget tree, and clicking one of these buttons closes all pins of the rendertarget except the pin for that button. So for example, if you click the Camera button, only the Octane camera pins would be expanded, and all other pins collapsed.
Paul