Firefox issue when navigating back to a previous page

[kimlai]

Firefox version: 76.0
instant.page version: 5.0.1

When navigating to a new page, and then navigating back using the browser's back button, the cursor is shown as "grabbing", as if the user was dragging the <a> tag that was previously clicked.

I created a minimal repo deployed to github pages to demonstrate the issue.

This does not happen when using the data-instant-no-mousedown-shortcut option.

It seems that when you navigate away on "mousedown", Firefox does not really understand that you released the mouse, so when you go back to the page it thinks you're still grabbing the element. I'm not sure if that's a Firefox bug or a instant.page bug though.