text properties in tex mode

[Kostas Oikonomou]

Hello,

I use Emacs's plain TeX mode (i.e. not AucTeX), with 
font-lock deactivated. (And Emacs 22.3.)

I'd like to be able to change the background color of a 
piece of text to, say, yellow, by selecting it with the 
mouse, and then doing Edit -> Text Properties -> Background 
Color.

However this fails with a message "Face ((:background 
yellow)) not configured for latex mode".
How do I get around this?

Thanks very much.

                                                Kostas