> Seriously, is it normal for LCDs to get warm during operation?

If they have a backlight, yes, because LEDs and CCFLs are only about 10% 
efficient at converting electrical energy to visible light.  A typical 
monitor might need around 5W of backlighting power, most of that is 
converted to heat.

> ...is 50 N a lot?

About 5 kg.  Significantly higher than the force you usually use to 
write/press with.

> Heee, do you remember the old laptops with the blue/purple monochrome 
> LCDs? Where if you touched the screen, the whole picture rippled slightly?

They still do, if you don't have any protection on the front.  My two 
monitors and my laptop screen here certainly do.

> [Actually, our photocopier has a display like that. And I think it needs a 
> screen saver, cos some of the controls are well burnt into it! I didn't 
> think LCDs could "burn" like that?]

They can if you don't keep the average voltage across each pixel exactly 
zero volts.  A bad/cheap driving circuit can easily allow enough of a DC 
voltage to start to screw things up after years of operation.  However 
usually the burn-in is not permanent, and disappears after some period (can 
be up to an hour or so with very slow displays).  Must admit I don't know 
the details because the displays we work on are not allowed to have any 
visible burn-in at all.

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