Set Active Project Command (File Menu)

The command activate the selected project so that Build and Run menu commands will be applied to that project. To use the command select a project in the Workspace Window and select Set Active Project command from the File menu or from the context menu.

Use this command when your workspace contains more than one project, or when you need to free or release all the currently used resource from the current active project, that includes unloading all DLL Libraries (not .net)  and closing all handles used by the current active project. This will occur even if the new active project is the same as the current project.

For more information see also Abort Command (Run Menu), Reset Command (Run Menu)