Product Version: NetBeans IDE Dev (Build 20080219062323)
Java: 1.5.0_12; Java HotSpot(TM) Client VM 1.5.0_12-b04
System: Windows XP version 5.1 running on x86; Cp1252; en_US (nb)

Select main menu Tools|Options > Miscellaneous > Ant tab. The a11y-tester tool output is like following:
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No Accessible name :
   Class: javax.swing.JList {  |  N/A }
   Class: javax.swing.JTabbedPane {  |  }
No Accessible description :
   Class: javax.swing.JButton {  Browse... |  }
   Class: javax.swing.JButton {  Default |  }
   Class: javax.swing.JCheckBox {  Always Show Output |  }
   Class: javax.swing.JCheckBox {  Reuse Output Tabs from Finished Processes |  }
   Class: javax.swing.JCheckBox {  Save All Modified Files Before Running Ant |  }
   Class: javax.swing.JComboBox {  Verbosity Level: |  }
   Class: javax.swing.JTabbedPane {  |  }
   Class: javax.swing.JTextField {  Ant Home: |  }
Components with no LABEL_FOR pointing to it :
   Class: javax.swing.JEditorPane {  Properties |  N/A }
   Class: javax.swing.JList {  |  N/A }
   Class: javax.swing.JTabbedPane {  |  }
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It seems that the relevant is only following:
-JList accessible name and description should be added
-Classpath label should be label for the JList and its mnemonic should be assigned