According to information leaked from PCPortal.org.ru, Windows 9 will support screen resolutions up to 8K, double the current Windows 8.1. In the picture above is the new size of the File Explorer icon found on Windows 9 Technical Preview with maximum size 768 x 768 pixels and the picture below is the display scaling (DPI Scaling) based on the pixel density of the the screen. 

Currently only 8K resolution TV appearances while the largest resolution on computer screen now belongs to the Dell UltraSharp 27 monitor Ultra HD 5K. It is hoped that with the support of Windows 9, the next year will have more equipment and higher resolution screen appears. 9 on Windows user devices may also experience a better quality display with graphic interface elements, applications icon high resolution.