How do scroll up bars perform vs. bars that disappear / reappear on click (ie. http://demos.jquerymobile.com/1.4.0/toolbar-fixed/ http://demos.jquerymobile.com/

How do scroll up bars perform vs. bars that disappear / reappear on click (ie. http://demos.jquerymobile.com/1.4.0/toolbar-fixed/ http://demos.jquerymobile.com/1.4.0/toolbar-fixed/), anybody know? http://ux.stackexchange.com/questions/57990/how-usable-are-bars-that-disappear-reappear-on-scroll http://ux.stackexchange.com/questions/57990/how-usable-are-b...