Manage opened projects with Projects panel
In Projects panel, all opened projects are organized by type in a tree.

You can activate a project by double-clicking it or pressing Return on the keyboard.

To close projects, you can select the projects and choose Close Selected Projects in the shortcut menu. By right clicking on a folder, you can choose a menu item in the shortcut menu to close all projects of that type.

You may select audio file projects then use drag-drop to add files to mixspace, CD project and batch processor also.