I managed to find a work-around for this frustrating feature!
It should be do-able without major programming skills (use with caution, your mileage may vary). The goal is to run the following bit of JavaScript on the page where the speedgrader tool lives. It runs every 5 milliseconds (see "5" in the last line, feel free to change), and does two simple things. First, it hides the pop-up window asking you to confirm the annotation (so you don't accidently click it). Second, it clicks the "confirm" checkbox. This happens so quickly you shouldn't see anything, and the features is effectively gone. Note: all lines will be stored as individual annotations, and can cause lag if there are too many.
setInterval(function() {
if (document.querySelector('.AnnotationToolbar-container'))
document.querySelector('.AnnotationToolbar-container').hidden = 1
if (document.querySelector('button[aria-label="create annotation"]'))
document.querySelector('button[aria-label="create annotation"]').click();
}, 5);
If you know what you're doing, you can run this many ways. If you don't, one relatively simple approach on Chrome is to install the CJS2 extension, which runs code anytime a given website URL is active (alternatives may be available for other browsers). After adding CJS2, clicking on the CJS2 Chrome icon will open a window where you can paste the above code, click save, and be finished. However, this must be done the first time while on a page in the correct domain, and it isn't "https://canvas...." Instead, we have to get to "https://canvadocs.instructure.com" (and this must ultimately be the URL listed in CJS2!).
Unfortunately, from what I can tell, CJS2 won't let you paste in the correct URL, and visiting it directly just redirects. To get to it while in speedgrader, click ctrl+shift+i to get to dev tools, click on the "Elements" tab, and use ctrl+f to search for "canvadoc". It should highlight a line that begins with:
<iframe src="/api/v1/canvadoc_session?
There should be a URL contained within. Right click this and open in a new tab. Now proceed with the above instructions to open CJS2 and paste in the code. You should now see the correct URL. Save and test. You can always disable this or remove CJS2 if it causes any issues.
This discussion post is outdated and has been archived. Please use the Community question forums and official documentation for the most current and accurate information.