I'm using my 770 as a display for an automatically-refreshing web page. This works fine.

I'm running Microb in full screen mode and have it set to not show the toolbar. Whenever the page refreshes, the toolbar flashes up at the bottom while the page loads. This is distracting, especially as the page is mostly dark.

Is there a setting that will keep the toolbar hidden in full screen, even while a page is loading?

don't think so. This is a standard in the interface, also happens in fx. rss reader, browser with opera engine.