Crowley was formerly a program manager on Microsoft's IE team, while Heller worked as a consultant for Microsoft on IE issues for more than six years.
Company IT administrators can set access to IE6-specific sites and applications via group policies within IE8, giving them complete control over when IE8 mutates into IE6. The add-on works on any version of Windows that supports IE8, including XP, Vista and Windows 7.
Unibrows targets organizations that want to move beyond Windows XP without having to redesign internal sites and revamp Web apps to make them compatible with IE8, said Heller. Some firms that have been beta testing the add-on plan to use it as a temporary stop-gap, while others hope to use it for several years.
One large manufacturing company in the U.K. that's testing Unibrows wants the add-on so it can migrate to Windows 7 now but hold off remaking its mission-critical CRM (customer relationship management) Web application until 2013, said Heller.
"We do see an obsolescence curve for Unibrows," Heller admitted, "but it will be years before organizations won't need IE6."
Microsoft will retire IE6 and its companion OS, Windows XP, from all support in April 2014, when it issues the final security updates for the software.
"But there are always going to be browser compatibility issues," said Crowley, adding that the technology behind Unibrows can be used to create similar add-ons for other browsers to provide backward compatibility with sites and online applications.
According to the latest statistics from site analytics vendor Net Applications, IE6 accounted for 15% of all browsers used last month worldwide. At its pace of decline over the past year, IE6 won't drop under the 10% mark until May 2011, and will still retain a share of more than 5% -- as much as Apple 's Safari currently controls -- by this time next year.
Browsium has been beta testing Unibrows since July, and will ship a final version later this month, said Heller. "We're very close to release," he said.
Unibrows will be sold on a per-seat basis for $5 per user per year, said Heller.
More information about the add-on can be found on Browsium's Web site .