double Cue dots break:

Overscan areas aren't intended to be seen (hence the name). Pointless and unnecessary it may be, with modern TVs, but we're pretty much stuck with it. Broadcasters need to use it because TVs expect it, and TVs expect it because broadcasters use it.

David

I have seen the cue dots on the current series of The X Factor, though nobody else seems to have spotted them.
Older programs had cue dots burnt in to them. You can sometimes see them on the home video releases or TV repeats.
Of course, while we're on the nostalgic trail, cue dots were originally a cinema invention to tell the projectionist when to change the reels.

Most LCDs (I don't know about plasmas) these days have a Just Scan mode anyway, so technician menu access is unnecessary.

Even so, the overscan areas of LCDs are a lot smaller than most, if not all CRTs.

Often Just Scan (and Full Pixel or 1:1) can only be selected when driving the display at its native resolution though.

Both Sony Full 1080 panels we have can only run with no overscan in 1080i or 1080p mode. When fed 720p, 576i/p or 480i/p you can reduce it, but not totally remove it.

Of course the LCD/Plasma overscan is purely a scaling issue - and a choice made by manufacturers. All fixed pixel displays (plasmas, LCDs, DLPs, DILAs etc.) could run with none...

(Broadcasters don't expect full images to be seen - particularly in SD where half lines, blanking/timing differences and DVE stuff mean you don't get nice clean image edges...)

I was asking about this on the other place recently as I'd had my eye on a TV that had a resolution of 1366 x 768 and had been wondering if that would make the picture inferior in any way.

1366x768 displays were pretty common at one point, as Full 1080 panels were originally quite expensive to manufacture. However they have the disadvantage that 1920x1080 and 1280x720 (the two HD formats) both have to be scaled to fit the 1366x768 display resolution, and obviously don't deliver the full HD resolution that Blu-ray at 1920x1080/24p can deliver. For small screen sizes this may not be a major issue (depends on viewing distance obviously) - but once you get to 37" and above it could be -again it depends on viewing distance.

Many 1366x768 displays also have permanent overscan on non-native resolutions - and in fact some won't accept their native resolution as an input format at all, or if they do it is via an analogue VGA input and stuck at 60Hz (which is pants if you want to watch European SD/HD TV via your PC - as we're 50Hz here) Some models do allow you to feed 1366x768 via HDMI (or DVI) and some allow you to feed this at 50Hz - though getting a PC to feed at this resolution can also be an issue.

For some reason 1280x720 LCD panels were never really produced in large numbers (which would at least favour 1280x720 HD content) - I think because 1366x768 is a 16:9 version of 1024x768 which is a more PC-friendly resolution? If you plan on feeding a PC to the screen, then native resolution is important, along with 1:1 pixel mapping, as without these you end up with very blurry text as it has been scaled)

(I have a small 22" 1680x1050 - 16:10 - HDTV for my bedroom, and my PC doesn't like feeding it 1680x1050 at 50Hz only at 60Hz - and I haven't had time to delve into creating a custom mode)

They're actually the main cue rather than a back up for talkback. A buzzer will sound to coincide with the cue dot appearing so the TC is aware it is showing and then it is down to them to watch for it to dissapear.
As previously mentioned, cue dots are only now used on live programming and even then only for live breaks.

They were often known as "cigarette burns", as they were circular rings in the film.

If it's only for live programming, why did it just appear on the Jeremy Kyle Show... and that's not live (the one broadcast today was recorded in on October 25th at 3.30pm).

The cue-dots have also appeared recently on Emmerdale and Coronation Street, just like normal, 30 seconds before the break. Yes, they're networked programmes and not live, but I suppose in theory they use them to cue adverts now.

I've no idea - just looked at the logger and there's no cue dot there at the end of part 3!

Then, as has already been said, you are not setting your TV up properly, because overscan areas are not meant to be seen. Presumably you also set your picture up with bars, PLUGE and test cards too?

I noticed the other day that one of the news agencies, Reuters, are soon introducing a cue dot to their live feeds for the same reason. I'm not sure where that will be in the frame but it probably won't be visible on those news services that are 16:9 (which all the UK ones are)