Bug 40300 Compiler pref page does not disable unavailable preferences [build path]
I20030716 + plug-in export If I set a parent preference to ignore I'd expect that sub-properties get disabled.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/preferences/CompilerConfigurationBlock.java
Text text= addTextField(composite, label, PREF_PB_MAX_PER_UNIT, 0, 0);
		text.setTextLimit(6);
		text.setLayoutData(gd);
		return composite;
	}
	private Composite createUnusedCodeTabContent(TabFolder folder) {
		String[] errorWarningIgnore= new String[] { ERROR, WARNING, IGNORE };
		
		String[] errorWarningIgnoreLabels= new String[] {
			PreferencesMessages.getString("CompilerConfigurationBlock.error"),  
			PreferencesMessages.getString("CompilerConfigurationBlock.warning"), 
			PreferencesMessages.getString("CompilerConfigurationBlock.ignore") 
		};
		
		String[] enabledDisabled= new String[] { ENABLED, DISABLED };
		
		int nColumns= 3;
		
		GridLayout layout= new GridLayout();
		layout.numColumns= nColumns;
					
		Composite composite= new Composite(folder, SWT.NULL);
		composite.setLayout(layout);
		Label description= new Label(composite, SWT.WRAP);
		description.setText(PreferencesMessages.getString("CompilerConfigurationBlock.unused.description")); 
		GridData gd= new GridData();
		gd.horizontalSpan= nColumns;
		gd.widthHint= fPixelConverter.convertWidthInCharsToPixels(50);
		description.setLayoutData(gd);