Background graphics bleed into the foreground UI through the fixed transparency at times. This reduces the functionality of UI elements. A pretty standard window transparency slider would restore functionality.
Changing graphics drivers didnt fix it.
Turning off addons didnt fix it.
Resetting settings file didnt fix it.
Turning off HDR didnt fix it.
Resetting AMD shader cache didn't fix it.
Deleting shader.cooked didnt fix it.