Hello. I just got a fresh installation of Linux Mint 13 MATE 64-bit. I installed compiz and emerald right out of the box, and everything was working perfectly with the default gtk theme. Nevertheless, for the sake of customization I changed the gtk theme, but I have come accross the same problems with all of the custom themes I've tried to install (using the appearance menu). I have tested themes that announce themselves both as gtk2.0 and gtk3.0. Among the "ugly results" are specific programs with the default ugly themes (the one that makes stuff look like Windows 95). An example of these programs is synaptic. I have also noticed some features of the theme not working properly, such as grayed out options. When the default themes show properly grayed out options, all custom themes appear to show an old default (picture included, note the difference in the graying out of the stop icon). I think I fixed this in the past by installing a gtk engine, but I am unsure if this will truly solve the problem, and I also dont remember which engine.