Add triple dots on Import button

[TheEvilSkeleton]

Licensing

• I confirm that this is either my code or was released under the terms of a GPLv3-or-later compatible license. Also I agree to release it here under the terms of the GPLv3-or-later.

Description

This adds triple dots next to the Import button. This is the standard for GNOME applications.

Linked Issue

Ref. #95