SmartGit and SmartSVN by default come with a US-English dictionary. To use spell-checking for other languages, you can use, e.g. LibreOffice dictionaries. Please rename the .oxt file extension to .zip and unpack the *.aff and *.dic files into the same directory of your choice. Now you can create a new dictionary in the SmartGit or SmartSVN preferences by selecting the *.dic file.