Firefox/Feature Brainstorming/Notification Tools:Title Flash Notification
From MozillaWiki
Several popular social network sites and gmail provide web based chat facilities. Chat notifications are indicated by the flashing of the title bar, which results in the Firefox tab flashing also. However if you have Firefox minimised, and the title of a tab which is currently not being displayed is flashed, there's no way for the user to know from their Firefox taskbar icon. My suggestion is that Firefox provides some optional notification mechanism that can flash the main Firefox window if any tab within it flashes.