Strange resizing in Windows 10

I’ve just updated to Windows 10. And I notice that some of the apps and my Unity apps when you resize the window widthwise to beyond a certain point the app compresses to a thin rectangles with black bars either side.

Does anyone know what version will sort this problem out? If I change it to Windows 8.1 Universal app for instance?

I believe they currently target Windows 8.

Here is a screenshot (not my app but shows the general idea:)

This is expected. Back in Windows 8.0, apps were only required to support horizontal resolutions bigger than 1024, and if user resizes the window to be small enough, it would snap it to the side with the fixed size of 320. They removed this limitation in Windows 8.1, but for backwards compatibility, these apps still behave the same way.

To fix it, build your application for Windows 8.1 SDK.

Thanks. I guess I’ll have to make a Windows 8.1 version.