If you look at that old thread, I had to convert webdings.ttf and wingding.ttf to
.otf, then back to
.ttf, before they would render properly in GIMP. I think this apples to several other ding style fonts, as well and it's still the case in GIMP 2.8.x.
I have not seen an explanation, as to why GIMP can't render those dings properly. However, converting them to an OpenType Font, then back to a TrueType Font, corrected whatever problem there was. I used this site to do the conversion.
http://www.freefontconverter.com/