Explorer splits its own command line on commas, so a gallery path such as
output\a,\Windows\System32\calc.exe,b\x.png escaped the roots through
[explorer, "/select,", path] (security review H1). Windows now selects the
file with ILCreateFromPathW and SHOpenFolderAndSelectItems, and on any shell
failure falls back to os.startfile on the folder. No process is started.