[news.eclipse.platform] how to contribute to problems view

["Nick Tan" <missedone@xxxxxxxxx>]

Hi, all:

I want to contribute an action to problems view, I take this,
http://wiki.eclipse.org/Menu_Contributions/Problems_View_Example
as a reference, but:
1. my action is always disabled
2. I can't find the OpenMarkerHandler handler because I'd like to "monkey 
and see it", how to get the problem entry object. It's wired, I searched all 
the source code.

Any advice is appreciated.
Thanks in advanced.

Nick