Issue when losing focus from the comments on a grade item in the gradebook when using the ATTO editor on Firefox

This is a very odd issue, but we've been able to reproduce it on multiple machines with multiple courses under multiple accounts, so it looks like it might be some sort of odd bug going on.

This will be a bit hard to describe, so please bear with me and ask questions if I don't do a good job of explaining the issue.

When a professor logs into Moodle, they get the screen that says courses with assignments that need graded. If they click on the link, it will take them to the page that shows the list of assignment submissions.

On this page, if you click the down arrow next to the Edit option, then click on the Grade option, you're taken to the Submission Status page.

If you start to type in the "Feedback Comments" section at the bottom, then click on the assignment file, it'll ask you "This page is asking you to confirm that you want to leave - date you have entered may not be saved." You have to click on the "Leave Page" button to get the file to open, but it doesn't redirect you away from the page itself.

When you do this, you can open the file and view it. When you then go back to the Moodle page (either with ALT+TAB or using the mouse) :

• the cursor keys don't work in the "feedback comments" box (eg., using the UDLR keys on the keyboard don't actually move around in the text box)
• the blinking cursor itself disappears from the text box
• positioning your mouse cursor is the only way to change where text is inserted
• the formatting buttons on the toolbar don't do anything

We've reproduced this on several machines under different classes (including "fake" classes we made just to test,) different users, etc., and the issue is reproducible consistently. To get cursor control or formatting back, you have to cancel out, then go back into the assignment, or cause the page to reload somehow, so it almost looks like the editor needs to be reinstantiated for it to start working again.

However, it only happens on Firefox, and only when using the ATTO editor. Switching the user to TinyMCE, using Chrome, etc. seems to not have an issue. Also, running firebug when reproducing the error doesn't turn up anything at all.