Here's a simple tip which turns your side column Inbox notification text into a simple new icon that is already built-in to your base theme layout. I just thought this method is more noticeable so I have shared this tip. You don't need to upload any images just insert these few lines or copy and paste the attachment code text below into your custom code box and you're all set.
Sample screen shot:
Language Editor Version (with unread count, easy & more integrated)
Go to your Language Editor and search for the keyword 'new'. You can find the target field around mid part of the search result (Page 3) or sample link here:
Search for <span %1$s>%2$s</span> new and replace it with:
Hit 'Save' and the new changes should take effect.
Latest: With unread messages count (Load time fix)
Choose your version and enjoy!
We got such a feature available as a widget subscription that is currently in beta. Contact me if you might be interested, I'll send you the details.
Here is something else that can be done with language editor fyi