I use Squarespace to host my blog. Most of the time it is wonderful, but the web based page editing is a bit of a pain to be honest. One of the things I really hate is this dialogue, which appears if you click outside the post editing window.
It carefully explains what Discard and Save do, while neglecting to tell you anything useful about Cancel, which is the button that you really should press.
Discard throws away your work, Save ends the editing session and closes the window (meaning that you have to open it again if you want to keep working on the post) and Cancel takes you back to editing the post, which is almost always what you want to do.