Bug 55399 exception on Code Style preference page
Nightly build 0319 - start a new eclipse install - show the Java > Code Style preference page - will get the attached exception
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/preferences/NameConventionConfigurationBlock.java
NameConventionInputDialog dialog= new NameConventionInputDialog(getShell(), title, message, entry);
		if (dialog.open() == Window.OK) {
			fNameConventionList.replaceElement(entry, dialog.getResult());
		}
	}		
	/* (non-Javadoc)
	 * @see org.eclipse.jdt.internal.ui.preferences.OptionsConfigurationBlock#performDefaults()
	 */
	public void performDefaults() {
		super.performDefaults();
		IPreferenceStore prefs= JavaPlugin.getDefault().getPreferenceStore();
		fExceptionName.setText(prefs.getDefaultString(PREF_EXCEPTION_NAME));
		fUseKeywordThisBox.setSelection(prefs.getDefaultBoolean(PREF_KEYWORD_THIS));
		fUseIsForBooleanGettersBox.setSelection(prefs.getDefaultBoolean(PREF_IS_FOR_GETTERS));
	}
	/* (non-Javadoc)
	 * @see org.eclipse.jdt.internal.ui.preferences.OptionsConfigurationBlock#performOk(boolean)
	 */
	public boolean performOk(boolean enabled) {
		IPreferenceStore prefs= PreferenceConstants.getPreferenceStore();
		prefs.setValue(PREF_EXCEPTION_NAME, fExceptionName.getText());
		prefs.setValue(PREF_KEYWORD_THIS, fUseKeywordThisBox.isSelected());
		prefs.setValue(PREF_IS_FOR_GETTERS, fUseIsForBooleanGettersBox.isSelected());
		JavaPlugin.getDefault().savePluginPreferences();
				
		packEntries();
		return super.performOk(enabled);
	}
}