BetaDesigns( Blog ).toString( );

Using FireFox as your main browser when developing on Windows means that by default you end up getting loads of tabs for all your canceled debug sessions. In order to prevent this behavior simply type in
about:config
into the address bar and do a search for
browser.link.open_external
then change it's value from 3 to 1; this will make your flex debug session always appear in one tab.