copy image of webengine doesn't work that can't paste image to other place

Test step:
Run demobrowser example and open wiki website.
Fox example : https://en.wikipedia.org/wiki/Main_Page.

I use ClipBook Viewer tool to test, you can download it form http://www.thewindowsclub.com/windows-clipboard-manager-viewer.

then clipboard show some error when i copy image form web content. it's work fine in chromium. Look at the attachment screenshot below: