Constraining an input field's contents to be a single line.

[Alex Tweedly]

I'm sure there must be an easy way I'm missing ..... he said in hope :-)

I want a field to contain a single line of data - i.. no CRs.

I've done the easy bit (a handler for returninfield).

I can even do the moderate bit -  a 'pastekey' handler, and check for 
CRs in the clipboard - but that doesn't apply to mobile (or at least, 
the dict says it doesn't).

Is there any way to handle it on mobile ?

Thanks
Alex.