I have my NGUI set up to draw out two UI's side by side. This is because my game is running 2 viewports to support 3D output.
I've got user input restricted to viewport 1 only.
When I interact with a UI object on viewport 1, I need to make the viewport 2 UI elements state mirror that of viewport 1. As they are 2 components of the same interface.
I previously used one UI with two camera, but I've since duplicated the UI to allow some elements to have 3D effects.
examples.
Checkbox1, is clicked and checked. Checkbox2 must also check.
Slider1, moves. Slider2 must move to match.