I use Double Commander [DC] as my default file manager in replacement of Windows' Explorer. To this end I defined
Windows Registry Editor Version 5.00
[HKEY_CLASSES_ROOT\Directory\shell]
@="open"
[HKEY_CLASSES_ROOT\Directory\shell\open\command]
@="\"C:\\Program Files\\Double Commander\\doublecmd.exe\" -C -T \"%1\""
as suggested here. This tweak does what it should, however it makes Windows' Explorer unusable as clicks on folders trigger the open command which is redirected to the new file manager (it should still be usable as a fallback in case DC does not work).
I was wondering if it would be possible to define a separate \shell\open\command for Windows' Explorer or other software, as an exception to the general rule defined above.