Courier text overwritten by following text

[Barrie Stott]

Suppose I have the following in a document set at 12pt ( and there is
nothing special about the `mmmmm' text):

        mmmmm {Courier Bold -5p} @Font {mmmmm} mmmmm

I would have expected the spaces between the three mmmmm's to be
similar but that between the second two depends on the Courier text
with some Courier text causing a nasty overlap. This prompts a couple
of questions.

Is this normal behaviour? Can anything be done to overcome it?

In case it is relevant I have a Debian Sarge system running lout-3.24.

Barrie.