Use your mouse to select some text below ...
When shall we three meet again
In thunder, lightning, or in rain?
When the hurlyburly's done,
When the battle's lost and won.
That is, just select the text and do not
press Ctrl+C. Double- and triple-clicks also
copy-on-select.
... and paste it into this text box.
Now try to select text from the box below ...
This works only if you check option "Copy-on-select in input elements" in the add-on preferences.
... and paste it into this text box.
But even that option does not help here ...
... and there is nothing this add-on can do about that or some other special cases. See the add-on homepage for more information.