Support for grouped rendered opacity?

[Randahl Fink Isaksen]

Is it possible to change the opacity of a rendered node tree rather than affecting the opacity of each individual node? When I am changing the opacity of a panel with multiple node children, what I am seeing is the individual opacities of each child node changing, which is not what I am aiming for.

In one pane I am rendering a 3D house using multiple 2D shapes, and I wish to make the pane fade away by gradually decreasing its opacity; but when I alter the opacity of the pane, what I am seeing is the individual walls of the house becoming semitransparent revealing the geometry of the house. What I was hoping to achieve was to change the opacity of the *rendered* pane. Is that possible?

Randahl