I don't know if that is important, but I experience that error only when I download the 0.6.x-versions directly from launchpad and then try to start the script within the folder tha is supposed to start Ubuntu Tweak. When installed via Synaptic, it works.
I don't know if that is important, but I experience that error only when I download the 0.6.x-versions directly from launchpad and then try to start the script within the folder tha is supposed to start Ubuntu Tweak. When installed via Synaptic, it works.