For those using the source editing interface, you may have noticed a radical change to the edit fields. Syntax highlighting is being implemented around Wikia. See Kirkburn's blog about syntax highlighting for more information, or to provide feedback.
Short description: Syntax highlighting colour codes elements within the editing interface. Templates are one colour, for example, while galleries are another.
If syntax highlighting is too much of a problem, you can enable / disable it by a check box in your preferences on the "Editing" tab. Please note however that your reasons for wanting it, or not wanting it, may constitute valuable feedback.