In Opera, a one-toolbar-setup can only be accomplished using the tabbar with it's parts tabbar head and tabbar tail used for controls and buttons. I had to learn quickly that tabbar head is not the best replacement for the addressbar since it will move up and down when (un-) maximizing the browser window. Tabbar tail can do the job better. To make it work, some skin changes became necessary which are (with other redesigns) included in version 2.70+ of my Z1-Glass skin. You can get it here.
The one-toolbar-setup has one huge (and currently unsolvable) problem in Opera: The addressfield will reduce to minimal width when placed in tabbar head/tail. You can type still fine then, but you can't read a lot of the address and (even worse) the popup below will be also limited in it's width. I strongly suggest to the Opera devs to make it possible to resize the addressfield when placed in tabbar head/tail, since maximized space for the page is a very valuable goal and IE9 set the bar a lot higher than before. If you would like to support my suggestion, I made a wish-list-forum posting about it.
Anyway, if you can live with the drawbacks, here is how it can be done in Opera: