The Advanced WordPress Theme Editor plugin will allow you to edit your theme directly in your blog admin section but with a better experience since it will format and highlight your source code with nice colours.
The plugin is compatible with WP 2.8 and less and is based on the Edit Area script that supports at least PHP, CSS, JS and many more file types.

Advanced WordPress Theme Editor

This plugin will improve your experience when editing yout wp themes since it will format and highlight your source code with nice colours.

ChubbyNinjaa

Do you get frustrated trying to work out what the template file you’re editing is? Ever had to echo/print some text to see if WordPress is picking up the file you expect it to?
If yes, then give this plugin a try, it simply adds a handy dropdown at the top of the admin bar giving you the ability to quickly see what theme template file(s) is being used, as well as what other files are being included, from themes and plugins.
Never get frustrated with creating child themes again, using Template Debugger you can generate a new child theme based on one of the installed parent themes, and Template Debugger does all the leg work! Just fill out the input fields and Template Debugger will create the theme directory, add in the style.css and functions.php
Plugin features:
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Quickly find out what template file(s) are being used
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See where they’re included
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See what plugin template files are in use
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Create new page templates from post editing screen
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Create child themes from a parent theme
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… Got an idea for a feature?? Cool! Drop me a message in the support forum
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Template Debugger

It make the process of theme customization so much easier, I use it on every WordPress website I develop !



A must have

useful

Intended for Developers: This template debugger helps you identify what template files are being used on the page you're viewing.

Advanced WordPress Theme Editor vs Template Debugger