I like the new file comparison extension - I've been using something similar as a custom command for years, but this is more elegant.
I have WinMerge installed as a portable application, and I thought maybe WinSCP would look in the registry to find the install path. However, looking at the code for the extension, it appears to expect the tool to be installed in the directory specified by %PF%. I assume this is the WinSCP directory, and we would install the tools in sub-folders there.
I have hacked the file to give the full path to WinMerge - however, it's not elegant. Is there another way to specify this path?