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/OptionsConfigurationBlock.java
for (int i= 0; i < allKeys.length; i++) {
				if (settings.get(allKeys[i]) != null) {
					return true;
				}
			}
		}
		return false;
	}	
		
	protected final void setOptions(Map map) {
		if (fProject != null) {
			fProject.setOptions(map);
		} else {
			JavaCore.setOptions((Hashtable) map);
		}	
	} 
	
	protected Shell getShell() {
		return fShell;
	}
	
	protected void setShell(Shell shell) {
		fShell= shell;
	}	
	
	protected abstract Control createContents(Composite parent);
	
	protected void addCheckBox(Composite parent, String label, String key, String[] values, int indent) {
		ControlData data= new ControlData(key, values);