In Guido, a Source File represents a self-contained piece of a project. Source files are accessed via the Project Manager plugin , and can be opened in the configured editor (see Configuration), or in the FormBuilder if they are GUI source files. Certain properties of source files can be modified in the Property Editor. The properties of a source file will be made editable in the Property Editor when the source file is selected in the Property Manager's file listing.
The most common source file is a GUI source file such as a TkForm or TkComposite. TkForms represent a Tk window that is not expected to be embedded in another window. A Tk composite is very much like a TkForm except it is intended to be embedded into another TkForm.
Other types of non-GUI source files can be edited in their respective editors, as configured by their MIME type (see Configuration).