I used to apply Meld as external diff in a different environment.
Last time I used it is a while ago.

Now I tried to recreate that here.
I did not get it working.
It just does nothing at all, not even starting up the tool with some error.

I tried several suggestions in the options dialog.

Then I noticed one can watch and edit the .gitconfig file.
It observed SourceTree does overwrite it.
It also had created multiple void or erroneous 'cmd' lines.

I also did some experimentation on the file, directly or indirectly.
Currently I have the following lines.

[difftool "sourcetree"]
cmd = 'C:/Program Files/Meld/Meld.exe' \"$LOCAL\" \"$REMOTE\"
[mergetool "sourcetree"]
trustExitCode = true
cmd = 'C:/Program Files/Meld/Meld.exe' \"$LOCAL\" \"$BASE\" \"$REMOTE\" --auto-merge --output=\"$MERGED\"

Still dead.

What's this?