Debugging firefox extension

I like to make some changes to a firefox extension(DownThem All).

In that they have written Debug logs like:

Debug.log('<Whatever>'); 

I wanted to view those开发者_运维技巧 messages during execution, in order to make the changes effectively. How to view those messages (most preferably i wanted to set breakpoints and make inlace modification)?

I am running firefox 5.

tail -f the log file.

Or to stay in Firefox, DTA preferences->privacy->view log, and refresh manually or set a greasemonkey script to periodically refresh.

If you want to alter the extension, unzip the .xpi file to its' directory (DTA is {DD} in <profile>/extensions) and rename the .xpi, so Firefox will load the code from the directory, which you can alter at will.

For breakpoints etc, use firebug & chromebug.