Perhaps this is by design in the NGUI 3.0, but I wanted to check. I noticed that when we have a scrolling panel that is clipped, I can still click buttons on the scrolling panel that are outside the clipping area. This has lead to some confusion and bug reports, since testers tap on an empty area underneath a clipped panel, but it still reacts as though you've just clicked a button that is outside the clipping area.
It's possible to add additional colliders to block input outside of the clipped panel, but that seems like a hack that wasn't required with previous versions of NGUI. I also noticed that this seems to only happen when the UICamera Event Type is set to "World". Setting it to "UI" seems to behave correctly, but I haven't tested it thoroughly.
So, should input function this way, or is this a bug?