A DESCRIPTION OF THE REQUEST :
Nimbus currently (as of 6u10 build 13) does not support window decorations. I.e. getSupportsWindowDecorations() returns false and as expected in that case,
results in a JFrame with no decorations.
Since the Nimbus look and feel clashes with the platforms native look and feel in many cases, the combination of platform native decorations and nimbus controls can look awkward. Nimbus already has decorations for internal frames, perhaps it would not take much to support top-level window decorations so an application using the Nimbus look and feel can have a consistent look.