Contact Apple Developer Technical Support
 

The issue here is not that the DisplayLink software is broken. The second monitor works fine on the latest release. The problem is that when the software is active, it breaks several main line Apple applications like iPhoto, Preview, Keynote. Clearly the driver is using some "short cut" that compromises the OS. Probably a Category that has modified one of the core OS frameworks.

Whoever is responsible for this needs to contact Apple Developer Technical Support and explain that users of this device have reported bug 19081948 on Radar

Both Mark and I get CoreAnimation: rendering error 506. on our applications when the DisplayLink Software is active

This is not a bug in MacOS, it's the DisplayLink driver breaking Yosemite. MacOS works fine then the DisplayLink driver is uninstalled. Until this bug is fixed the hardware is junk.

Joseph