K3B doesn't have graphic icon for gnome users (only shortcut). Ugly... :-) There's is a easy fix. Mini-patch comming... Reproducible: Always Steps to Reproduce: 1. 2. 3.
Created attachment 34223 [details, diff] with this patch, gnome find the k3b icon. PD: The patch contains another minor-fix when you have the USE -kde (and k3bsetup2.desktop doesn't exists).
fixed in k3b-0.11.12-r1