Spaces around Emojione characters show up as boxes in GTK apps

[IBBoard]

If I use an Emojione supplied character in a GTK app then spaces to either side of it show up as a rectangle with four small rectangles in.

Example:

Text in the bottom is ❣ a b c ✄. Hexdump of that is:

00000000  20 20 20 e2 9d a3 20 20  20 61 20 62 20 63 20 e2  |   ...   a b c .|
00000010  9c 84 20 0a                                       |.. .|

Firefox renders those characters fine.

Steps to reproduce:

1. Install Emojione according to instructions in README
2. Type "space space space" followed by an emoji (e.g. "+:+)" for a smiley face in default Gnome ibus setup)

Behaviour: Spaces suddenly turn into boxes as soon as emoji is there

Expected: Spaces stay looking like spaces!

System: Gnome 3.16, GTK 3.16, openSUSE Leap 42.1

[13rac1]

Thank you for the thorough bug report! This is a duplicate of #2. I've come up with some possible solutions and would appreciate your thoughts in that issue. Thanks!