You can not scroll down a web page when trying to copy a portion of it.
If you highlight a portion of a web page to copy it to a document, you used to be able to scroll down the page with your mouse. You can't do that with Firefox 4. The only way to do it is to use the down arrow (with your other hand) to scroll down the page.
Wšykne wótegrona (3)
You need to have the Add-ons bar displayed (View > Toolbars > Add-ons Bar) to make that work.
I have noticed the same error. Until this is corrected, you can also use the wheel on your mouse to scroll down and highlight the area(s) you wish to on the screen.
Thank you. Very simple.