The rumors about Apple rolling out its third MacBook lineup with Retina display have been swirling around for months. And finally, app developers have started upgrading their apps with Retina display support. The support for pixel-dense panels fuels the rumors that MacBooks with Retina display are coming to Apple’s Worldwide Developer Conference (WWDC).

Evidences are on an increase that Apple is upgrading its MacBook lineup with Retina display which is currently found in iPhone 4S and the new iPad only. App Developer Brothers Roloff updated its file sync app FolderWatch on Thursday with Retina display support.

"Apple just approved FolderWatch 2.0.4. The app is ready for retina displays and comes with a couple handy new features," tweeted Brothers Roloff on Thursday.

Brothers Roloff has updated its app with Retina display support, but the app maker is denying the reports that it does not know anything about Apple's plans to update MacBook Pros with Retina display.

"By 'retina graphics' we're simply referring to HiDPI (a.k.a. @2x graphics). We don't know what Apple will show at WWDC," the app maker tweeted on Friday.

Folks at 9To5Mac also received images of detailed spec sheet that is believed to be associated with 15-inch model of MacBook Pro. If the report is to be believed, the MacBook Pro has 2,560 x 1,600 pixels resolution, which is enough dense in terms of pixel density to be labeled as "Retina display".

The Retina display is not the only update that MacBooks are expected to get at the WWDC event. Reportedly, the Apple laptops are also getting Ivy Bridge architecture and high-speed USB 3.0 ports as well as new designs.

WWDC is also likely to play host to the next generation Apple mobile operating system dubbed iOS 6, which is expected to debut Apple's in-house mapping app for iPhone and iPad along with deep Facebook integration.

The Worldwide Developer Conference begins June 11 and Apple may unveil the Retina display-powered MacBooks on the same day.