WordPress.org

Enables syntax highlighting in the integrated themes and plugins source code editors. Supports PHP, HTML, CSS and JS.
Effectively edit your themes or plugins when you only have access to a browser, by enabling syntax highlighting in WordPress integrated source code editors. Supports PHP, HTML, CSS and JavaScript

Features

• Mixed language Syntax highlighting (PHP,HTML,JavaScript and CSS)
• Smart Search (string or regex).
• Search and Replace.
• Full Screen editor.
• 11 editor themes.
• Multiple Undo & Redo (editor remembers all edits).
• AutoComplete with over 3500 WordPress Functions.
• Tested and Works with IE8,9,10 FF3.6 and up, chrome 8 and up.
• Ajax save file. (NEW)
• Ajax Create new file. (NEW)
• Ajax Delete file. (NEW)
• Ajax Create new directory. (NEW)
• Jump To Line with hot key Crtl + G. (NEW)
• File Tree View (NEW)
• Download theme button.(NEW)
• Download Plugin button.(NEW)
• Download file button.(NEW)
• Editor CodeFolding.(NEW)
• Toggle file tree on/off.(NEW)
• Download file button.(NEW)
• Comment code out/in.(NEW)
• Auto format and indenting code.(NEW)
• Built-in version control.(NEW)

any feedback or suggestions are welcome.

check out my other plugins

Also Credits to marijn for his excellent CodeMirror JS library : http://marijn.haverbeke.nl/codemirror/