Bug 63840 warning on unused labels
we have warnings for all sorts of unused things. one for unused labels would be good too.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/preferences/ProblemSeveritiesConfigurationBlock.java
inner= new Composite(excomposite, SWT.NONE);
		inner.setFont(composite.getFont());
		inner.setLayout(new GridLayout(nColumns, false));
		excomposite.setClient(inner);
		
		label= PreferencesMessages.ProblemSeveritiesConfigurationBlock_pb_static_access_receiver_label; 
		addComboBox(inner, label, PREF_PB_STATIC_ACCESS_RECEIVER, errorWarningIgnore, errorWarningIgnoreLabels, defaultIndent);
		
		label= PreferencesMessages.ProblemSeveritiesConfigurationBlock_pb_indirect_access_to_static_label; 
		addComboBox(inner, label, PREF_PB_INDIRECT_STATIC_ACCESS, errorWarningIgnore, errorWarningIgnoreLabels, defaultIndent);	
		label= PreferencesMessages.ProblemSeveritiesConfigurationBlock_pb_unqualified_field_access_label; 
		addComboBox(inner, label, PREF_PB_UNQUALIFIED_FIELD_ACCESS, errorWarningIgnore, errorWarningIgnoreLabels, defaultIndent);
		
		label= PreferencesMessages.ProblemSeveritiesConfigurationBlock_pb_undocumented_empty_block_label; 
		addComboBox(inner, label, PREF_PB_UNDOCUMENTED_EMPTY_BLOCK, errorWarningIgnore, errorWarningIgnoreLabels, defaultIndent);
		
		label= PreferencesMessages.ProblemSeveritiesConfigurationBlock_pb_synth_access_emul_label; 
		addComboBox(inner, label, PREF_PB_SYNTHETIC_ACCESS_EMULATION, errorWarningIgnore, errorWarningIgnoreLabels, defaultIndent);
		label= PreferencesMessages.ProblemSeveritiesConfigurationBlock_pb_method_naming_label; 
		addComboBox(inner, label, PREF_PB_METHOD_WITH_CONSTRUCTOR_NAME, errorWarningIgnore, errorWarningIgnoreLabels, defaultIndent);			
		label= PreferencesMessages.ProblemSeveritiesConfigurationBlock_pb_non_externalized_strings_label; 
		addComboBox(inner, label, PREF_PB_NON_EXTERNALIZED_STRINGS, errorWarningIgnore, errorWarningIgnoreLabels, defaultIndent);
		
		
		
		label= PreferencesMessages.ProblemSeveritiesConfigurationBlock_section_potential_programming_problems; 
		excomposite= createStyleSection(composite, label, nColumns);
		
		inner= new Composite(excomposite, SWT.NONE);
		inner.setFont(composite.getFont());