Diff detects comment and part of method as a diff unit
When two files are compared, the specific changes are highlighted with a darker color, inside the different blocks. This is useful, but when presented with different blocks, it may behave weirdly.
Since I cannot post images online, I have 7zipped the files to reproduce with the result image in a protected file under my domain.
The files can be found at this address: http://tests.alphasmanifesto.com/Merge-WrongDiffBlockHighligted.7z
The password for the file is "mergebegins" (without quotes).
I was testing the diff tool and it does not have a "report bug" button, but yes, I will do that when testing the merge tool.
Actually, you can use the "report bug" button on the merge tool to send us the 3 files you detected to have an issue :-)