I discovered Pixlr by using Google Drive to open an image in Pixlr Editor. This seems to have created a Pixlr account without setting up any password for the account. Now my Gmail address cannot be used to log in or sign up from within the Pixlr Editor.
I can, however, get logged in by using Google Drive to open an image with Pixlr Editor. Once logged in, clicking 'Settings' does nothing, so I have no way to manage the account.
I'm concerned that others discovering Pixlr through Google Drive may encounter the same problem, but may not find the work-around.