The editor will attempt to colorize documents according to their MIME type, which is determined by the file extension, or content. For example, any file ending in .py will be colorized as a Python source code document. Any file whose MIME type cannot be determined will display all text in black normal font by default.
All the available colorization document types are listed in the File Properties dialog's File Attributes tab. If you have a file that is not being recognized automatically, you can use the File Type menu found there to alter the way the file is being displayed. Your selections from this menu are stored in your project file, so changes made are permanent in the context of that project.
If you have many files with an unrecognized extension, use the Extra File Types preference to add your extension.
Syntax coloring can be configured as described in the section Syntax Coloring.