Currently, Decker is limited to working with US-ASCII text; I apologize for this inconvenience to those who use other alphabets and glyphs.
You can, however, customize any of the fonts (including built-in fonts) to replace a few punctuation characters with glyphs you're missing. The example deck "fontedit" is one way to do this:
I also wrote this post describing how to build your own tools for importing bitmapped fonts and converting them into Decker's internal format.