To close the project file in the current window, choose Close Project from the Project menu. If you have changed or edited the project since it was last saved MPL will display a question dialog box that will ask whether you want to save the project file before you close it.
If you want to save the project file click on the OK button. If you do not want to save the project file click on the Cancel button and any changes you have made to the project file will be lost.