[edwintorok]

Are you using a serif font? Because sans-serif is very bad when it comes to representing source code: the characters 1lI and 0O all look alike. For example Pidgin's choice of a sans-serif font always caused me troubles, had to either switch the font, or the system-wide sans-serif font to something where I can tell the difference.

[seanmcdirmid]

Segoe UI. Honestly, I knew this would be a problem but I haven't had this problem yet. The most annoying thing is that subtraction (-) is too short in relation to addition (+).

[Silhouette]

In my ideal world, code would be typeset in proportional fonts, with mathematically appropriate glyphs chosen from a font with a comprehensive Unicode character set, including a proper minus instead of hyphen-minus.

The usual problems with this are arranging indentations/alignments neatly where you really do want them and avoiding an explosion of funny characters once you've got a large part of the Unicode character set to play with. Tools are pretty good at the first these days, but pity the poor Haskell developers if we don't fix the second. People will be writing logging libraries that use different levels of emoticon to save writing 'debug' and 'error'...