Need Help Rated 5 out of 5 stars

The inner structure of "firbug" has changed since the addon has been updated to version 2, and it also brings me a problem:
In the older version, the toolbaricon of firebug is in the location "\skin\classic", and when I replace the png files such as "firebug16.png" and "firebug16Disabled.png" with other png file I modified, the toolbaricon will be changed.
But when I updated firebug, I tried and failed to locate those files and thus cannot make the modification(I aslo tried base64 code, but failed too).
plz help!

This review is for a previous version of the add-on (2.0.1-signed).