The folder is identified at the top of the dialog box as a Custom folder.

Dialog box options

 

Folder name

Type the name you want to give the new folder.

File extensions

Type the extensions of files you want placed in this folder. Type a semicolon (;) between extensions. No period is needed before the extension. The extensions must be different from those in the Standard project folders, because only one folder may hold a file of a given extension.