Activate math mode. Type 2^Q. Select it, then use the math panel and
change the font to "normal text mode \textrm"
Note that view->dvi fails, as lyx now generates invalid latex.
The bug exists in lyx 1.3 too, where it also happen when you
write 2^Q as text and then selects it and converts it to math.
Lyx 1.4 does the right thing in this latter case, but can still
be forced to fail by changing to the \textrm font.
The text mode may be invalid for some mathematical constructs.
Refusing the font change is better than silently generating bad latex.
Not 1.4.0 material I guess, but reported to bugzilla so it
won't get lost.
Helge Hafting