You can learn how to build the standard source code package on your platform (POSIX, Linux, BSD, MacOS) reading the U++ online documentation.
New low-overhead CoWork parallelization method / pattern - Loop
Throughout the Core, many rvalue / universal reference related optimizations
CoPartition optimized to perform the work in calling thread if data size is small
SeedRandom without parameter now reseeds the random with host entropy
Array/Vector new Get/Set methods
New features for WebSocket client mode
plugin/bz2: Streaming support
Co Option to run parallel
BufferPainter::PreClipDashed
In Windows, owned windows now have minimize box disabled (as minimizing of owned windows leads to strange behaviour)
LineEdit::WhenScroll event
New OptionBox widget (Option with LabelBox like graphics, also able to automatically enable/disable contained widgets)
FileSel now has option to add widgets into the dialog (e.g. to specify save format)
Very long files (>400MB) are now opened for view rather than edit.
Some trivial merge conflict helper tools
IconDes improvements
Esc scripting language now has 'continue' statement