Mediabar Container application (Desktop application) - Looking for suggestions on the opt technology

Question

I need to develop an application with the below features

1. Desktop - Media bar container application
2. Should work in Windows, MAC & Linux
3. Media bar will have Ads, Tickers & Other third party applications
4. Have to write Engine & GUI
5. Involves multi threading

Anyone could suggest the opt technology for developing the same would be appreciated.

We have planned to do it in QT. But few suggest Adobe AIR.

Answer 1

I heard a lot of good things about 'Java':-)