Sun Microsystems' desktop division CTO has defected to Adobe Systems. It's the latest installment of musical chairs between vendors jockeying for developers building rich internet applications, and highlights Sun's weaknesses in this already competitive field.

Twenty-one year Sun veteran Hans Muller this week started working at Adobe Systems on Flex, the company's cross-platform framework for building media applications for different browsers, desktops and operating systems.

Muller spent his days at Sun focused on GUIs, leading all of the company's client Java work. Muller also led Java Community Process efforts on a "simple" application framework for Swing desktop applications. He has now pulled back from this gig.

While not the first Sun employee to join Adobe this year working on Flex, Muller is certainly the highest ranking. Chet Haase, an architect in Sun's Java client group and author of Filthy Rich Clients: Developing Animated and Graphical Effects for Desktop Java Applications joined Adobe in February.

A Sun spokesperson told Reg Dev Muller and Haase had left voluntarily and neither had been laid off, as part of the plan to cut between 1,500 and 2,500 staff by the end of this year to reduce costs.

Both departures follow former Sun software executive vice president John Loiacono's exit. The well-coiffed one joined Adobe in March 2006 as vice president of the creative solutions business responsible for Flash along with content creation tools. Loiacono served nineteen years with Sun.

The fact that Muller and Haase jumped rather then being pushed won't look good for Sun or its RIA strategy.

A trend appears to be emerging among those working in Sun's RIA technologies to find a home with a company where the technology is more established - read: actually exists - and the job prospects potentially more secure.

A year since announcing JavaFX at JavaOne 2007, Sun still has no finished code. The company instead used this month's JavaOne to promise "early access" tools in July, with a version of JavaFX for the desktop in the "autumn". JavaFX for cell phones and TVs are not due until next spring - two years after Sun unveiled JavaFX at JavaOne 2007.