Created attachment 1445250 [details]
Screenshot of Gnome Font Viewer after step 3

Description of problem:

I want to install a font. When I double click the font file in Nautilus, the Gnome Font Viewer opens. I can click install, but I do not get visible feedback if the installation was successful or not.

Version-Release number of selected component (if applicable):

Name         : gnome-font-viewer
Version      : 3.28.0
Release      : 1.fc28
Arch         : x86_64
Size         : 637 k
Source       : gnome-font-viewer-3.28.0-1.fc28.src.rpm
Repo         : @System
From repo    : anaconda

How reproducible:

- Everytime

Steps to Reproduce:

1. Download a new font (e. g. FontAwesome Free https://fontawesome.com/)
2. Open file manager and double click the font file
3. In Gnome Font Viewer, click on the blue "Install" button
4. Clickt the blue "Install" button again

Actual results:

After step 3, the blue install button doesn't change and there is no feedback (e. g. popup or so) if the installation was successful or not. After step 4, the install button is grayed out and reads "Install Failed" (see attached screenshots).

In the background, the font gets installed at step 3, but I do not get visible feedback.

Expected results:

I get informed if installation was successful or not, e. g. "Install" button becomes disabled and reads "Installed".

Additional info: