bug#18195: 24.3.92; window-screen-lines is not accurate

[martin rudalics]

>> This would have to be done on the Lisp level by selecting some font
>> before calculating the size of the overlay.
>
> Which font would you select?  I'm talking about a situation where the
> text over which the candidate list will be popped uses several
> different fonts, and so each line of the buffer text has a different
> height.

I would pop up that list in a temporary buffer and run
`window-text-pixel-size' over it.

>> But I have problems with the attached patch.  If I invoke
>> `window-text-pixel-size' with a different buffer than that displayed
>> in the window I get an arguments out of range error.  Any ideas?
>
> You switched the current buffer, but not the buffer pointed to by
> w->contents.

That was the problem, indeed.

Thanks, martin