A testcase to reproduce this issue is attached.
Steps to reproduce this issue:
2. you can see the value of one of the attributes of the self-defined composite component at 'Panel1'
2. click 'Panel2'
3. click 'Panel1'
4. value at 'Panel1' is not shown anymore. (if you refresh the page with 'F5' after that, the value is there again)
This behaviour occurs with the latest myfaces-2.1.2-SNAPSHOT (30.06.2011)
With an older version of myfaces-2.1.2-SNAPSHOT (22.06.2011) and with myfaces-2.1.1 everything works as expected.