Instead of GtkEventBox use GtkButton for the lock icons.
GtkEventBox does not have any visual feedback that it
actually can be pressed. As in: If you don't know that this
is an area for interaction it is not obvious.
Using Gtk.ReliefStyle.NONE on the GtkButton keeps the old
styling but still gives feedback when hovering over the
buttons.
Co-authored-by: Christian Tacke <8560110+ChristianTacke@users.noreply.github.com>