This is where I do all my personal testing. You are welcome to use this sandbox, just don't remove any of my test edits. I don't use the Commons Sandbox because it gets erased like every second by some user who wants to test his page blanking skills. No offense to anyone who's job is to blank out pages.
Image notes sandbox
This is a "sandbox" for trying out image annotations. You can try out image notes on the image below. Don't worry, all your changes are visible on this page only; you won't corrupt existing notes at the file page.
Start by clicking the button above.