Bug 82231 [build path] Hard to find type restriction compiler problem preferences
I20050104-1600 There compiler preference page contains a Warning/Error node with many sub-entries . I tried to find where I could change the 'warning' for the access of internal types to 'error'. No luck until I realized that the Build node also contains Warning/Error settings.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/wizards/buildpaths/LibrariesWorkbookPage.java
boolean noAttributes= containsOnlyTopLevelEntries(selElements);
		fLibrariesList.enableButton(IDX_ADDEXT, noAttributes);
		fLibrariesList.enableButton(IDX_ADDFOL, noAttributes);
		fLibrariesList.enableButton(IDX_ADDJAR, noAttributes);
		fLibrariesList.enableButton(IDX_ADDLIB, noAttributes);
		fLibrariesList.enableButton(IDX_ADDVAR, noAttributes);
	}
	
	private boolean canEdit(List selElements) {
		if (selElements.size() != 1) {
			return false;
		}
		Object elem= selElements.get(0);
		if (elem instanceof CPListElement) {
			CPListElement curr= (CPListElement) elem;
			return !(curr.getResource() instanceof IFolder) && curr.getParentContainer() == null;
		}
		if (elem instanceof CPListElementAttribute) {
			CPListElementAttribute attrib= (CPListElementAttribute) elem;
			if (attrib.isInNonModifiableContainer()) {
				return false;
			}
			return true;
		}
		return false;
	}
	
	private void libaryPageDialogFieldChanged(DialogField field) {
		if (fCurrJProject != null) {