You must be logged into Yahoo, for this add-on to work!
The difference between this and the other add-ons are: This add-on only fetches a small data (kb) instead of the full page (mb) what the other add-ons are doing. For this reason, i decided to create my own notifier for Yahoo.
Note: If you have the setting "Show mail preview popup" enabled, you can still open yahoo mail in a new tab by middle-clicking on the toolbar icon.
