You can check the path to the external editor with this code in the command line of the Browser Console.

viewSourceAppPath = Components.classes["@mozilla.org/preferences-service;1"]
.getService(Components.interfaces.nsIPrefBranch)
.getComplexValue("view_source.editor.path",Components.interfaces.nsIFile);
viewSourceAppPath.path;

You can open the Browser Console (3-bar Menu button or Tools > Web Developer). Toggle devtools.chrome.enabled to true on the about:config page to enable the command line in the Browser Console.

• https://developer.mozilla.org/Tools/Browser_Console

Paste the JavaScript code in the command line. Press the Enter key to evaluate the JavaScript code.

Thank you cor-el.

'[Exception... "Component returned failure code: 0x80520001 (NS_ERROR_FILE_UNRECOGNIZED_PATH) [nsIPrefBranch.getComplexValue]" nsresult: "0x80520001 (NS_ERROR_FILE_UNRECOGNIZED_PATH)" location: "JS frame :: debugger eval code :: <TOP_LEVEL> :: line 1" data: no]'

This is what I got back - I don't understand it. The path in About:Config was copied/pasted directly out of the shortcut's Properties --> Target. Looking at it in About: Config it is identical to that target. So I do not understand why it is returning an ERROR_FILE_UNRECOGNIZED_PATH.

That could possibly mean that this pref doesn't exist or have an incorrect path name that can't be resolved to a local path.

What is the current value of the file path?

Did you make sure that the view_source.editor.path exists and that view_source.editor.external is true. If you need to pass parameters, see: view_source.editor.args

As a test, I just went into IE Web Developer Tools. I selected Customize IE View Source and pointed it to the editor in the same location as I put into About:Config. IE found it and now when I open IE HTML source it does it using my editor. So as IE can do it, the problem must be within FF.

To answer your questions: 1) yes, it exists (see above) 2) Yes, it is set.

The value of the FP is: "C:\Kedit16\KEDITW32.exe"

See attached snapshot of About:Config.

Try to escape the backslashes: "C:\\Kedit16\\KEDITW32.exe"

Thanks for the suggestion, cor-el. But it didn't fix it.

Hmm, I tested with Notepad++

With the path from the shortcut --

"C:\Program Files (x86)\Notepad++\notepad++.exe"

-- it was ignored and Firefox displayed the source in a tab.

However, it worked when I removed the quotation marks:

C:\Program Files (x86)\Notepad++\notepad++.exe

That's surprising, since there's a space in the path.

What if you edit out the quotation marks on yours?

Success!! That was it. I removed the quotation marks and it works!.

Thank you jscher300 for taking the time to try it and to help me!! I truly appreciate it very much!