Adds a few handy links to Yahoo! Mail.
The links added will let you select unread and read mails separately. You'll also see 2 more links to select all and unselect all mails, but this is redundant since Yahoo! mail provides it already.
This extension is NOT for the new Yahoo! mail beta.
There is nothing very special in this extension. I made it because I need the functionality... and I thought there is no harm in sharing it. Once the beta version becomes widespread, this extension will be obsolete.