Table headers are not compliant with Nimbus L&F. I'm not sure about the proper component, please reassing if necessary.
Created attachment 62263 [details]
improper appearance of plugin table headers (Nimbus)
Also, note that the window shading is incorrect and please fix together with this issue. Thanks.
the problem with table headers is common for all platforms (e.g. win xp), the following fix should take care of it,
don't know about the window shading though
Integrated into 'main-golden', available in build *200808231401* on http://bits.netbeans.org/dev/nightly/
User: S. Aubrecht <firstname.lastname@example.org>
Log: #136284 - wrong table header borders
IMHO it's fixed.