I changed LightDm's theme using Ubuntu-Tweak on Ubuntu 13.04. LightDm did not show the changes. Instead, LightDm lacks a background (solid purplish-pink) and uses odd-looking icons. I decided to undo my changes. I tried reinstalling LightDm, but that did not work. What could I try? Would doing a complete removal in Synaptic work followed by a fresh LightDm install? I cannot fix the theme using Ubuntu-Tweak.