Bug 4240 Can't edit class path entry (1GKEPIF)
There is no way to edit an existing entry for a library on the Java Build Path project properties page (other than editing the .classpath file directly). NOTES: EG (9/22/2001 11:42:11 AM) this is particularly annoying for variables. we should have an Edit button when a variable is selected.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/wizards/buildpaths/LibrariesWorkbookPage.java
return null;
	}
	
	private CPListElement[] chooseContainerEntry(ClasspathContainerDescriptor desc) {
		ClasspathContainerWizard wizard= new ClasspathContainerWizard(desc);
		
		WizardDialog dialog= new WizardDialog(getShell(), wizard);
		PixelConverter converter= new PixelConverter(getShell());
		
		dialog.setMinimumPageSize(converter.convertWidthInCharsToPixels(40), converter.convertHeightInCharsToPixels(20));
		dialog.create();
		dialog.getShell().setText(NewWizardMessages.getString("LibrariesWorkbookPage.ContainerDialog.title")); 
		if (dialog.open() == dialog.OK) {
			IClasspathEntry created= wizard.getNewEntry();
			if (created != null) {			
				CPListElement elem= new CPListElement(fCurrJProject, IClasspathEntry.CPE_CONTAINER, created.getPath(), null);
				return new CPListElement[] { elem };
			}
		}			
		return null;
	}	
	
	
	private void addAttachmentsFromExistingLibs(CPListElement elem) {
		if (elem.getEntryKind() == IClasspathEntry.CPE_CONTAINER) {
			return;
		}
		
		try {
			IJavaModel jmodel= fCurrJProject.getJavaModel();