The default image File:Echo Notifications new message indicator.png, which renders as shown here in English, may be changed by a translated version (uploaded on Wikimedia Commons with the same category, under the same name but with a suffix for the distinct language), notably for RTL languages as the layout of the bar is different.
If a version with high resolution is used for (created by capturing it from a zoomed in page, with antialias rendering of text enabled in your browser), you should append to this filename a pipe (
|) followed by a width not exceeding about
370px (Commons will generate several thumbnails, at 1.5x and 2x scales, allowing the browser to select automatically the version matching the display resolution of the browser) ; this size adjustment works better if the width of the captured image is about 740 pixels, and captured when viewing the page with a 200% zoom in your browser.
Make sure you include just the bar and the icon with the user name and possibly the Preferences link (which may be partially truncated). Crop your capture to include just a small white margin.
This image should also be anonymized if you capture a screenshot displaying your user name that you don’t want to advertize, by blurring the username.