I second the suspicion that, most likely, this is a issue with the Parallels graphics driver.
After issuing the ticket, I have been experimenting with Gnome and, as outlined above, have also seen graphics glitches in Gnome 3D mode (2D is fine). For testing purposes, I have further installed the very first Ubuntu 12.04(.0) package which comes with older versions of X and compiz. However, same flickering issue with Unity panel and launcher.
Browsing the web for flickering bugs like the ones described here (mainly on native installations), one encounters recommendations on driver update, uninstall, or reinstall. As further outlined in my first post, tweaking the rendering method to full screen redraw in CCSM (Compiz Config Settings Manager) makes the flickering go away. Unfortunately, this kind of rendering is not at all an acceptable workaround.
I guess we have no other option than waiting for Parallels to fix the graphics driver/emulation (asap).
Last edited: Oct 31, 2013