Hello Alan. I tried once. One dried properly, the others went mouldy! Are you using a pad or a laptop? I don't think smileys work on a pad.
You can do it very, very, very slowly in a low oven, as it is unlikely we will ever get enough sun here to do it properly outdoors. They don't taste quite the same as when done in the sun, but aren't bad at all.
Yes I do them in the oven on about 130, not too sure how long for though I'm afraid - until they look good.Here's what I do (adopted from my Brazilian housemate years ago):
Cut the tomatoes in half, place on very well olive oiled tray and sprinkle with salt, sugar and oregano (dried fine). Cook for at least an hour. If they are browning at all turn the oven down.
Once done, store in a jar with olive oil, including the oil from the tray.
I don't know how long they keep as they never make it into the jar in my household.
That's how I've done them too- possibly lower temp but my ovens seem to have nuclear capacity-make good roast potatoes because of it!
Alan on the browser there should a menu settings look for an item "request desktop site" and you should get the smilies.