bluenestbryan

This plugin adds the name and path of the theme (template) file used to generate the html page into the page’s source as a comment. It will also add the name of the header, footer and sidebar if they are included.
This is useful for debugging and seeing what template file generated a page.
To use, activate, then reload any open pages. In the HTML comments, you can search for “TEMPLATE INFO” to see the added comments with the names of the template files included.

Template File Name Debugger

Add the name of the theme (template) files used to generate a page into the page's
source as a comment.

水野史土

This plugin outputs a source code of the function/class you specified.
This plugin uses Syntaxhighlighter http://alexgorbatchev.com/SyntaxHighlighter/

Source View

This plugin outputs a source code of the function/class you specified.

Template File Name Debugger vs Source View