'Solved' this myself now. What happened is that the game remembers where you've put the tabs as if the displays were in that exact position always, even if you change the positions. I had set the screens up one above the other, saved, left the game. Then when I came back in I changed the displays to side by side, opened the game and tabs were missing. In fact, the game was putting them on the display as if it were one above the other, though the top monitor now no longer existed, because I had them side by side. That's what it remembered though - one above the other. So I set it up like that again and there they all were!! I dragged them all back down to the main screen again, THEN re-arranged the monitors side by side and put the tabs where I wanted them. Perhaps it's not a bug. But it will pay to remember, if you're messing around with multiple monitors, that this is how the game behaves. It does mean, for example, that if you set the game up on two monitors, with tabs on one and map on another, then close it leaving them like that, then (because you go out with your laptop, say) if you want to play as normal on one screen only, you will find that the tabs are all stuck on the virtual second screen. So, if you want flexibility, always manually move all your tabs back to the map screen before you quit!! (And this includes the types of tab not accessible from the side bar tab selector - the force info tab {and a shift click extra force info tab if you used one} and the task edit tab - you must open these and drag them back to your map screen before you quit!!)
