Bug 120544 [build path] Editing external source folder does not persist
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/wizards/buildpaths/BuildPathsBlock.java
if (Display.getCurrent() != null) {
			IStatus res= findMostSevereStatus();
			fContext.statusChanged(res);
		}
	}
	
	private IStatus findMostSevereStatus() {
		return StatusUtil.getMostSevere(new IStatus[] { fClassPathStatus, fOutputFolderStatus, fBuildPathStatus });
	}
	
	
	/**
	 * Validates the build path.
	 */
	public void updateClassPathStatus() {
		fClassPathStatus.setOK();
		
		List elements= fClassPathList.getElements();
	
		CPListElement entryMissing= null;
		int nEntriesMissing= 0;
		IClasspathEntry[] entries= new IClasspathEntry[elements.size()];
		for (int i= elements.size()-1 ; i >= 0 ; i--) {
			CPListElement currElement= (CPListElement)elements.get(i);
			boolean isChecked= fClassPathList.isChecked(currElement);
			if (currElement.getEntryKind() == IClasspathEntry.CPE_SOURCE) {
				if (!isChecked) {
					fClassPathList.setCheckedWithoutUpdate(currElement, true);
				}
				if (!fClassPathList.isGrayed(currElement)) {