I'm getting something similar. I think it's some incompatibility between the libraries in the scratchbox and the Xephyr display I'm connecting to.

If I use the Xephyr which came with the Maemo SDK VM (so Ubuntu 10.04) it works fine. But if I point DISPLAY to a Xephyr on my Debian 7 desktop, I get a large number of the "ClutterX11 - Failed to get XImage of pixmap" warnings. Some things are drawn okay, but even a simple Qt app with just a pushbutton fails to show the button.