The Project menu allows you to perform actions (builds or compilations) on projects in the Workbench.
This command opens the currently selected project or projects. The selected projects must currently be closed for this command to be available.
This command closes the currently selected project or projects. The selected projects must be currently open for this command to be available. Closing a project will remove all of that project's state from memory, but the contents on disk are left untouched.