Application.CaptureScreenshot with UI

I notice that as of the new UI (introduced in 4.6, but I'm running 5.1.3f1), calling Application.CaptureScreenshot does not include the UI in the capture. In fact it seems to flash off screen for a frame as though Unity thought it would be helpful to get rid of the UI when screenshotting, but in my case I need the UI included, and I also need a double-res capture.

So, I have a two-part question:

1. Can I tell Unity to capture UI when calling Application.CaptureScreenshot?

2. If not, can I use another approach to double-res capture?

Thanks everybody.