The other day I wanted to use a condensed font, and I though I had a choice of two: DejaVu Serif Condensed and DejaVu Sans Condensed. The "condensed" option is listed in the Format Character menu of OpenOffice, but if I choose it, nothing happens.
So, I investigated. In a font, you should be able to specify a family, like "DejaVu Sans", and a Style, like "bold" or "oblique". It seems that OpenOffice will only accept certain style names — oblique, italic, bold, or extra-light are OK, but condensed or small-caps are unacceptable! Many designers obviously know that, as they have created separate families like "DejaVu Sans Condensed" or "Fontin SmallCaps". Unfortunately, that doesn't necessarily work.
Gedit, the Gimp, and the Opcion font viewer treat them correctly, as separate fonts. On the other hand, OpenOffice, Dia, and Gnucharmap treat Fontin SmallCaps as a font, but DejaVu Sans Condensed as a variant (which OO then ignores), despite their internal names being handled in the same way.
The annoying thing is that one never knows who to complain to. Do OpenOffice, Dia, and Gnucharmap misbehave because they are relying on something else, or because they've copied each other's code?