Cannot Display Colour Emojis with gtk+-3.22.24

[John Frankish <john frankish outlook com>]

Hi,

I'm trying to display colour emojis with gtk+-3.22.24, cairo-1.15.8, pango-1.40.12, fontconfig-2.12.6, 
freetype-2.8.1 and harfbuzz-1.6.0.

I can get black and white emojis without problems, but cannot display colour emojis with, for example, 
gedit-3.22.1.

Is there a trick to this? Do only certain gtk3 apps display colour emojis?

John