The text pane in Blogger's edit page is rather cramped and becomes full when you're writing more than a couple of paragraphs. After looking at Blogger Wide Screen Editor, I thought it should be possible to write a style to automatically fit the edit box in a browser's window.
My Blogger full window width edit box style just changes the width of <div> elements from fixed values to
auto so the edit box can fill the width of the window. A bonus of this technique is that the tabs and controls automatically stay close to the right hand border when you resize your browser's window.
Just to avoid unplanned effects on the Blogger pages, I've set my style to only be applied to Blogger's post pages using url-prefix("http://www.blogger.com/post").