Qt 6.0 Beta Released
Upcoming Qt 6 is very exciting. The improvements they have made really makes it shine as a single application framework to develop cross platform applications that can run on mac, windows, linux, ios, and android. You can also target embedded systems.
Qt is a C++ development framework. It includes a declarative user interface markup language called QML. Qt 6 really builds up the C++ integration with QML in exciting new ways (bring the best of QML to C++).
Latest Information Update
QT 6 has hit another significant milestone. The Qt 6.0 Beta is released. Putting ease of mind into everyone counting on a Qt 6 release in early 2021
Here is Lars Knoll's Nov 2020 keynote talk on Qt6 - What's Cooking. It details the latest up to the minute status of imminent Qt 6.
For more information on what improvements Qt6 will bring, Lars gave a longer keynote at the end of 2019 that is very informative. This longer keynote presentation is titled 'Qt 6 will bring massive improvements to QML and 3D development'.
There is also a 10/26/20 post on Graphics in Qt 6.0 by a less interesting speaker available here.