GTK warning Theme parsing error

[Philippe-M]

Describe the bug
Flameshot does not launch and in my terminal I have the error:

(flameshot:613): Gtk-WARNING **: 09:31:32.950: Theme parsing error: gtk.css:3841:23: Junk at end of value for outline-offset

To Reproduce
Start flameshot

Expected behavior
A clear and concise description of what you expected to happen.

Desktop (please complete the following information):

• OS: Fedora
• Version 28 (last update)

[AlfredoRamos]

The issue is not related to Flameshot, is a GTK theme issue.

Update your GTK theme, you can ignore the warning or report to its creator.

Related issues #193

[chiddekel]

Level higher - how resolve parsing error ...
Gtk-WARNING **: 15:21:41.659: Theme parsing error: < data >:1:34: Expected ')' in color definition
What is data of this < data > ?

[AlfredoRamos]

@chiddekel You should seek for support with the author of the theme you're using, it's not an issue of Flameshot.