As Michael said, you need a font that supports Unicode. The ones with most broad support are Iso10646 fonts. Assuming Linux with X11, launch xfontsel
to find them. Select iso10646
from the rgstry
drop-down menu. Then fmly
menu will list available fonts with that encoding. Some are very limited, but
-*-fixed-medium-*-*-*-18-*-*-*-*-*-iso10646-*
is a good choice that comes with the X11 installation.
Then, you need either to set that font as a fallback in your Motif program or supply the resource via command-line
xmprogram -xrm '*fontList: -*-fixed-medium-*-*-*-18-*-*-*-*-*-iso10646-*'
If all worked right, there will be no problems with accented characters anymore.
For a font supporting even more glyphs, consider GNU Unifont.