I often use the space bar for scrolling pages in Firefox. When I have read the last line in the browser window I scroll down a page with the space bar so that the last line becomes the top line. So far so good, but when I'm almost at the end of a page and scroll down to the bottom of the page the last line moves to... somewhere between the top and the bottom. In this case I have to skim through the text to find where I were.
My question is basically if there is a plugin for Firefox which temporarily highlights the line which was previously the last line when scrolling with the space bar.