elementary OS Developer here, I believe GTK 3.10 (and we use GTK+ for all our apps) will be the first GTK version with High DPI support, so I'm not 100% sure re

elementary OS Developer here, I believe GTK 3.10 (and we use GTK+ for all our apps) will be the first GTK version with High DPI support, so I'm not 100% sure retina will work perfectly (you'd have to try). Also, I'm no pro on this, I'm not even sure if retina is that high DPI feature they keep talking about. However, if it is, Luna+1 (code name for next version of elementary OS) will use GTK 3.10 (or a newer one) for sure.