Thanks! Fixed. Note though RE your example generator, the defer attribute is not valid for 'inline' scripts - it's only valid for URL/remote scripts (i.e. using src attribute instead of writing text between the opening and closing script tags). Here are some options for running code after everything else has executed:

• document.addEventListener("DOMContentLoaded", function() { yourCodeHere }) - this is usually your best option (and by coincidence was already supported, since Cocell reported a similar issue a week or so ago)
• window.addEventListener("load", function() { yourCodeHere }) - same as window.onload = function() { yourCodeHere } but addEventListener a much better approach because it doesn't overwrite the onload function that might have been set by some other code (e.g. if you're writing a plugin, you might overwrite the importer's onload function that they set). With the addEventListener approach you can add as many as you want. But in general using window's load event isn't desirable because it also waits for stuff like images to finish loading before triggering. But if that's what you want, then use this.
• As you mentioned, you can put a square block at the end of the HTML panel like [ yourCodeHere ], but note that this will run again after every update(). If you only want it to run once, you'd have to write something like [doneStuffAlready ? "" : doStuff(), doneStuffAlready=true]