Search is broken differently. Right after the XenForo conversion, I was able to click on the magnifying glass and get a Search dialog. I could fiddle with settings, or go to Advanced, where Thread Search did not work. The point is, I could try.
Now, I click on magnifying glass, dialog appears, dialog disappears, I get "Search results for '*'". I have no chance to change anything, or go to Advanced. Leaning on the glass to try to get a context menu, to open in a new tab, does not help -- no context menu.
UPDATE: Operator error. I don't know why I started tapping the magnifying glass. If I tap in the "Search..." text box, the dialog box sits still, giving me time to do what I want.