HeaderSpan is loosing columns in Showcase app

[abthere]

It looks like there's a problem in the current version that can be demonstrated using the Showcase application grid_appearance_header_spans example.
Problem description:
Individual columns are moving outside HeaderSpan where they were initially.
Steps to reproduce:
1. navigate to grid_appearance_header_spans example http://www.smartclient.com/smartgwt/showcase/#grid_appearance_header_spans
2. right click on Country column, select columns and uncheck Capital column within Government & Politics HeaderSpan
3. uncheck the entire Government & Politics HeaderSpan
4. make Government & Politics HeaderSpan visible again
5. make Capital column visible.
Capital column will "jump out" of its parent HeaderSpan. Column show/hide menu will show Capital outside HeaderSpan.
The issue can be replicated using Firefox 13.0.1, Google Chrome 20.0.1132.57 m and IE 9.
I've tested it locally using v8.2p_2012-07-18/EVAL Deployment 2012-07-18 as well as Isomorphic hosted Showcase

Please let me know if there's a workaround or a fix.

[Isomorphic]

We believe this issue is already resolved in the 3.1d branch, could you try the latest nightly from that branch and let us know if you continue to see the problem

Thanks
Isomorphic Software

[abthere]

It appears to be resolved in 3.1d Looks very nice, thank you!