Comment 46 for bug 1192599

I think there are two related but separate issues discussed here. The original description focuses on the jumping screen effect caused by toolbars appearing and disappearing, whereas comment 5, comment 13 and comment 16 are rather about bug 38850, which speaks of the automatic disappearance of a toolbar as an issue in itself.

Appearing and disappearing toolbars may sometimes be problematic even when positioned at the bottom, as described in bug 55855.