Navigation toolbar cannot accept flexible space

I customize the navigation toolbar to include a flexible space at the end of the URL field. The purpose is to ensude that all the standard buttons are avaialble to the right of that field. I hit DONE and there is no change to the toolbar other then the 'X" ( stop this site) is missing and not accessible. The "x" become accessible only if I move it to the left of the URL. I can only get 4 radio buttons to the right of the URL??