This is interesting I have my tabs placed to the left and it works fine. When the tabs are placed at the top however they cannot be clicked on from the edge of the screen. Placing the tabs on the left has always made sense to me since most websites are designed for resolutions that are far smaller than 1920 pixels. The real real estate is the vertical space. Placing the tabs on the left also allows me to have a small preview of the page without waiting for the mouse over. I understand this solution is not for everyone.

Opera seems to listen to the community relatively closely so hopefully these two issues can be solved in a future patch (or maybe even an extension).