Samsung dribbled out a few more details on Wednesday about the foldable phone destined to shake up the smartphone industry in 2019. 

The foldable phone will use two displays, members of Samsung's system software group said at an afternoon session for developers. There's a 7.3-inch interior display you see when the phone's fully unfolded in tablet mode, but when you close it up, a 4.5 exterior screen acts like the smartphone already in your pocket.

Samsung wouldn't reveal any further details about the handset's hardware, but did concede when I asked if the screens could be made of different materials. My guess is that we'll see Gorilla Glass cover glass on the 4.5-inch screen and a type of plastic to cover the interior screen. 

Although several brands are working on thin, foldable glass that can withstand bending hundreds of thousands of times without breaking, there's a strong chance that Samsung could follow in the footsteps of the Royole FlexPai foldable phone and use a type of polymer, a plastic, to cover the display material below. On Tuesday, Royole showed the FlexPai to a group of journalists in San Francisco. This device is on preorder in China and available to developers globally.

In addition, the 7.3-inch screen will be able to split into three active areas at once. For example, you might see a full-screen spread. Or, the screen might split into two areas, where you're able to view a sidebar. Let's say you want to message and see two other apps at once. You'd be able to multitask with all three on the foldable Galaxy phone.

That's Flipboard's initial vision for its app on Samsung's foldable phone, which the news aggregator shared at Samsung's behest to inspire app developers to make their own programs work on Samsung's foldable phone and future phones, too. Google's support for Samsung's foldable phone is key, because it widens support for multiple active Android windows on this type of hybrid device. 

Samsung and Google want you to jump seamlessly from using an app on the 4.5-inch screen to pick up exactly where you left off when you unfold the phone and start using its 7.3-inch display.

Samsung also revealed more details about the foldable phone's aspect ratios and resolution. 

7.3-inch display spec

• Resolution: 1,536x2,152
  
• Screen density: 420 dpi/ppi
  
• Aspect ratio: (4.2:3)
  

4.5-inch display spec

• Resolution: 1,960x840
  
• Screen density: 420 dpi/ppi
  
• Aspect ratio: (21:9)
  

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