By default, the IDL Workbench will add open project directories to the !PATH system variable. This means that files contained in the open project will be found by IDL for automatic compilation.

To change the default behavior, uncheck the Update IDL path check box on the IDL Project Properties page of the Project Properties dialog.

If you allow the IDL Workbench to manage the path for a project:

• If the managed project is open, the IDL Workbench will ensure that the project directory (including any subdirectories) is included in the list of directories specified by the !PATH system variable. If the directory is not already present in !PATH, it will be added at the end of the path specification.
• If the managed project is closed, the IDL Workbench will remove the project directory from the list of directories specified by the !PATH system variable unless the project directory is also specified by the IDL_PATH preference.
• If you need to control the exact location of a managed project’s directory in the path specification, add the directory to the IDL_PATH preference. If the directory appears in the IDL_PATH preference, the value of the Update IDL path check box on the IDL Project Properties page is ignored.