Shows an indicator at bottom right/left when there is one or more background network requests in progress.
The number on the indicator shows the number of background network requests in progress.
When it shows, by default it will be placed at bottom-right. When the mouse cursor is moved to the right half area of the page, the indicator will move itself to the bottom-left.
If the SHIFT key is held down, the indicator will stay. And when the mouse cursor is on it, a list of pending network request URLs will be shown.
