Bug 55884 Loading a user library from file does not warn when overwriting an existing library [build path]
Works in I2004032400010 + plug-in export for I200403240800 Add library 'mylib'. Save it. Change it. Load library from file. ==> should warn that 'mylib' gets changed.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/preferences/UserLibraryPreferencePage.java
}
	/*
	 * @see PreferencePage#performOk()
	 */
	public boolean performOk() {
		try {
			PlatformUI.getWorkbench().getProgressService().run(true, true, new IRunnableWithProgress() { 
				public void run(IProgressMonitor monitor) throws InvocationTargetException {
					try {
						if (monitor != null) {
							monitor= new NullProgressMonitor();
						}
						
						updateUserLibararies(monitor);
					} catch (CoreException e) {
						throw new InvocationTargetException(e);
					} finally {
						monitor.done();
					}
				}
			});
		} catch (InterruptedException e) {
			
		} catch (InvocationTargetException e) {
			String title= PreferencesMessages.getString("UserLibraryPreferencePage.config.error.title"); 
			String message= PreferencesMessages.getString("UserLibraryPreferencePage.config.error.message"); 
			ExceptionHandler.handle(e, getShell(), title, message);
		}
		return true;
	}