VisIt install on windows 7/10:
(1) download v2.12.3 and build to PC; use default dir (and record it), e.g.
  C:\Users\yjzhang\AppData\Local\Programs\LLNL\VisIt*

To read in nc4 files (visIT has issues with stack overflow with nc4):
(2) Go to NCAR and get their installer for the latest C library. As I write, this is 4.5.0 (netcdf4):
https://www.unidata.ucar.edu/software/netcdf/docs/winbin.html
(3) Complete the installation and record the install dir.
    Then copy all files in bin/ of the install dir to the VisIT dir in (1) to overwrite.

Plugin:
(1) copy or download plugin from DWR site:
    https://schism.water.ca.gov/ ->Library and Resources ->plugin for latest visIT version (2.12.3)
    (https://schism.water.ca.gov/library/-/document_library/view/13269859  -> choose 2.12.3)

    and put it in C:\Users\yjzhang\AppData\Roaming\LLNL\VisIt\databases   
    (some directories may not exist; in that case, create them instead)


After these steps you'll be able to use the windows version of VisIt.