This is a basic implementation of spoiler formatting that you see on other forums, but for the version of phpBB running on the imagine-publishing magazine websites.
Due to how the phpBB software alternates between different colour background the user will have to choose which background colour they need to hide their text.
Currently this does not work in Firefox due to how the script grabs the highlighted text out of the input field and puts colour tags around it. It has something to do with FF not allowing us to get the selected text in the input in this browser. It seems to work fine in Chrome and Chromium. IE and Edge are untested (feel free to log an issue if you see that it doesn't work in these other browsers, assuming tampermonkey is even available on MS browsers).