In Opera there is no such setting so that that preference is automatically performed when you do a search, but it can still be done. If you want the tab to open in the background, enter the text into the search box, then press ctrl + shift + enter instead of just enter. It's a little more cumbersome, and may be preferable to simply press enter then switch back to the previous tab, but it's there if you want to use it.
Hope this helps,
hi, am using a OPERA Beta 1, is possible to do a search but , that this search, opera do it in a new tab in the background?