Replace gucharmap with gnome-characters

[jbicha]

Consider replacing gucharmap with gnome-characters.

Ubuntu 17.10 won't be doing this but it has been proposed for 18.04 LTS:
https://launchpad.net/bugs/1713176

[cassidyjames]

I know we looked at both when deciding default apps. The reasoning, if I recall, was that gucharmap is more feature-complete and obviously usable right now compared to gnome-characters. But I'm sure it's something that could be revisited, especially if gnome-characters improves in the meantime.

[AndreaPasqualini]

Following up some years later, I've noticed that gnome-characters supports character search in the Activities Overview, while gucharmap does not. This search is a feature I use quite frequently, so I swapped the two applications in my install. You may want to reconsider the default app in future releases in the light of this feature, now that gnome-characters works quite well.