Thank you for the translation effort. In addition to the PO file, there are two files used for system integration that should have translations (adding Thai translations in src/usr/share/applications/diffuse.desktop and creating a windows-installer/th.isl file). I can manually update/create these files if someone can provide me with Thai translations for the following strings:
"Diffuse Merge Tool""Graphical tool for merging and comparing text files" "Uninstall Diffuse Merge Tool""Open With Diffuse Merge Tool""Main Files""Windows Shell Integration""Add the installation path to the search path" Cheers,Derrick

