Simple Checker for Gmail™ has one and only one job. Get you notified about the number of unread emails you have in your inbox folder in a distraction-free way. There is no desktop notification nor there is a sound notification. Only the badged toolbar updates when a new email receives or an email is moved from your inbox folder.
By default the extension is set to check the primary account, if you want to change this read the FAQs page.
1. Clicking on the toolbar button opens the attached account
2. To refresh the badge number, click on the toolbar button and leave the opened page for a few seconds.
FAQs page: http://add0n.com/simple-checker-for-gmail.html
Bug Reporting page: https://github.com/rNeomy/simple-checker-for-gmail/