Copying multi-line text on Firefox does not work properly.

[Kjaerandsen]

When trying to copy multi-line text in the editor using the Firefox browser the text copied to the clipboard is not the full highlighted section. For example in the editor when selecting the whole third example statement only a blank line is copied to the clipboard, while for other examples there are cases where some of the text is copied, but not all. Copying text on the first line only seems to function, but not the text which spans multiple lines.

This was tested using Firefox on a Windows 10 machine without any extensions. The same behaviour was present in the Ace.js kitchen sink demo. The same behaviour could not be recreated using Firefox on Ubuntu 22.04.3 LTS, where the copying worked as expected.