It seems to work very well. But, I'm not concerned with page load time. I would like to use this to determine when a page has finished loading.
I could do this (using an external program) by monitoring the PageLoad time button on the toolbar. When it is loading is sayss "?s". But, I can't "read" the button. What I can "read" however is the color of any pixels of the button (assuming I always leave the toolbar alone, keep the button in a constant place and don't play with other settings that would vary thebutton's location in the window. Very easy.)
Even testing the pixel colors is tricky. (you don't need the details). HOWEVER, if the background color of the button was ONE COLOR while loading and when the page loaded it changed TO ANOTHER COLOR, my task would be trivially simple.