When a project is closed, it can no longer be changed and its resources no longer appear in the PHP IDE, but still reside on the local file system. Closed projects require less memory. Also, since they are not examined during builds, closing a project can improve build time.
To close a project:
Select the project in one of the navigation views.
Click Close Project on the pop-up menu. The subfolders and files will merge into the project name and become unavailable.
To re-open the project:
Select the project in one of the navigation views.
Click Open Project on the pop-up menu. The subfolders and files will “open” from the project name and become available..