[glenra]

You mean so as to remember where you were last reading are on the page? But if you use the mouse to switch browser tabs, that arrow moves up to the top of the page, and if you use any of the controls at the bottom, it moves down. I guess one could very carefully leave the window at a specific place so as to preserve that arrow's position, but it's not an obvious thing to do. How are you using this feature that makes it an improvement over just letting your pointer itself mark the current reading position?