Avatar from Bloggeratto has put up a comprehensive post on how to get your blogger navbar to auto-hide like the Microsoft Windows taskbar. This means that after using the code from his post you can make the blogger navbar hidden and it appears only when one hovers the mouse cursor over the navbar section.
To view what I am talking about, just view Bloggeratto in Firefox and check out the navbar section. See how the navbar appears when you bring the mouse cursor near it and auto-hides when the mouse cursor is taken away. You can learn this hack on Bloggeratto from here.