Testing by Plugable of Mac OS X 10.9 (Mavericks) has exposed changes that will break multi-monitor setups that use Plugable USB display adapters or docking stations for more than one monitor. This includes configurations that are currently working under OS X 10.8.5 (Mountain Lion) and 10.7.5 (Lion). The testing was done on the Golden Master prerelease version of OS X 10.9 (13A598).
Plugable USB display adapters and docking stations use DisplayLink chipsets that send video information through USB to connected monitors. Changes in OS X version 10.9 appear to allow this process to work for only a single additional monitor- for a total of 2 displays. Adding a 3rd display seems to create issues with the display arrangement- specifically, forcing all the displays to operate in “mirror” mode rather than as “extended” displays, and losing the software settings that relate to the physical arrangement of the monitors. Currently, the only consistent workaround available is to manually reconfigure display arrangement whenever this error is encountered. Connecting only one display at a time may (or may not, behavior varies) help.
Support for DisplayLink-based USB display adapters was also broken in early versions of OS X 10.8, but were largely corrected in later versions. We suspect support will improve in a similar way for later versions of OS X 10.9.
For OS X customers with more than two displays- even if only one is USB attached via a Plugable dock or adapter- we recommend *not* upgrading to OS X 10.9 at this time. Especially if everything is functioning under the earlier version you are using, the launch version of Mavericks will likely create new issues.
We will test each new revision to OS X 10.9 as it comes out and will update our blog and other information outlets when these issues have been successfully addressed. We appreciate everyone’s patience with this- efforts to resolve this issue are ongoing. Subscribe to email updates on our blog, or follow us on Twitter or Facebook for news as it develops.