Under GTk L&F, menu with just menu items is painted just fine. However, if submenu is added into such menu, suddenly menu is painted with significantly bigger apce on its left side.
Such behaviour don't correspond with native (OS) gtk L&F.

I reproduced this error on Linux Ubuntu Feisty (7.04), jdk 1.6.0_02, no matter which theme (reproduced with default Human and others).

Attachments contain picture of Ubuntu Applications menu, picture of the problem and test case which shows the problem (packaged in zip as netbeans project).