If you're working with Open/Close events, it's quite cumbersome when you want to test your code. You have to close the app in both Domino Designer and Notes. I used to close the designer every time I wanted to test modified code.
During a chat, Tim Tripcony mentioned that you could close the apps in Designer from the Package Explorer. In Package Explorer, each app is shown as a project. To release the app from Designer, simply right click the project, and select close project. No need to remove the app from Designer or close Designer to release the app from memory.
Share and enjoy! :)