@Helge: Thank you so much, this helped immensely!
@Guenter:
> Also, using a narrower typewriter font may help. My favourite is "txtt"
> (which unfortunately needs to be configured "per hand": Set the GUI selector
> for monospaced to [Default] and put the line
>
> \renewcommand{\ttdefault}{txtt}
>
> in the custom LaTeX preamble.
This sounds good, but I don't understand the part "Set the GUI
selector for monospaced to [Default]"
How do I do that?
Thanks a lot, everyone!
Lastalda
