When creating a theme for public release, either for sale or for free, it should not contain any hidden files. If you are using a Mac, you know it creates hidden files named .DS_Store in every folder.
.DS_Store is a file that stores custom attributes of its containing folder, such as the position of icons or the choice of a background image. The name is an abbreviation of Desktop Services Store, reflecting its purpose.
To remove this file just follow the instructions below :
1. Open your Terminal.
2. Enter the following in the command line and press Enter.
find . -name '*.DS_Store' -type f -delete
the above command will remove the .DS_Store files throughout your computer.