Release notes for each V4 beta release are gathered here.
V4 is a major rewrite with changes on many levels so please be on the lookout for any bugs.
The main new functionality is that MoI is now a 64-bit program for both Windows and Mac and the Mac version is a native build and doesn't use Wineskin anymore.
New system requirements are Windows 7/8/10 64-bit or macOS 10.8 - 10.13 .
Polygon conversion can now use all your system memory instead of running into 32-bit memory limits.
A lot of various little quirky things should be tuned up for the Mac version.
The only known areas still not quite working yet are snap text labels and dotted/dashed line styles in viewports and Mac trackpad gestures aren't fully functional yet.