Unity is using something that looks like Emerald instead of the correct theme (like Metacity)

Question

I just upgraded my netbook thus: Lucid -> Maverick -> Natty. (I skipped Maverick other than as an upgrade step due to issues with Unity.)

Now, I seem to be stuck with something that looks like Emerald but apparently isn't (see note below). Compiz is running, as is gtk-window-decorator, but my title bars aren't following Ubuntu's theme. I was using the Ambiance theme with no problems until the upgrade to Natty.

Here's a screenshot:

How can I get the default theme?

Note: I never installed Emerald, and as far as I can tell it isn't installed. There's no running process containing the string emerald. So I'm not sure where gtk-window-decorator is getting its configuration from.

Edit

Following htorque's very reasonable suggestion to run unity --reset made matters worse. Now, after logging out/in, most of my theme-related stuff is gone entirely and can't be changed (clicking on the themes in the dialog changes the title bar/scrollbar color but nothing else). Here's a screenshot of the current situation:

Answer 1

This doesn't seem to be Emerald, but an undecorated Metacity.

I worked this out using Ubuntu Tweak, since I forgot where the option was in gconf-editor.

If you haven't installed it yet, you can do so by:

sudo add-apt-repository ppa:tualatrix/ppa && sudo apt-get update

sudo apt-get install ubuntu-tweak

Once installed, open it up, and head to Window Manager Settings, under the Desktop section. Scroll down, and the option for "Use Metacity window theme" under Window Effects should be unchecked in your present condition. Check it, and it should bring up the correct theme. If not, restart Compiz.

Hope that works! :)

Answer 2

Try running

unity --reset

This should reset your Compiz profile to Unity's defaults (e.g., the window decorator should be /usr/bin/compiz-decorator).