估算可用浏览器区域的好方法

I'm trying to figure out the best way to estimate the maximum size of the browser viewable area. i.e. the screen dimensions less toolbars, bookmarks, etc. Obviously it wont be perfect for cases when the window isn't maximized and due to the fact that people do actually use different browsers - I'm just looking for a good estimate here.I'm trying to figure out the best way to estima