FWIW, it&#x27;s generally a bad idea to mix in testing and unstable in a stable system (or even just testing). My recommendation is to run stable along with backports (<i>if</i> needed) -- and use something like <i>schroot</i>[1] for running persistent (separate) sessions under testing, unstable etc.<p>Schroot essentially wraps up debootstrap and chroot along with mounting &#x2F;proc etc, and (optionally) bind-mounting &#x2F;home (which among other things gives access to x11 session cookies, for sharing one xorg display -- so one could run firefox, gimp or mplayr from an unstable-chroot on a stable system). Overall, with SSD prices dropping as sizes are increasing -- it might be better to simply use vms (one of the nice (potential) things about rkt -- the ability to run a &quot;container&quot; under kvm, turning it into a vm).<p>[1] <a href="https:&#x2F;&#x2F;wiki.debian.org&#x2F;Schroot" rel="nofollow">https:&#x2F;&#x2F;wiki.debian.org&#x2F;Schroot</a>