May I make a suggestion:
The code for Zen Tools calls this image for every Zen Tools instance in the site and appears in the administration.
http://zentools.joomlabamboo.com/images/zentools400.png
Firstly why reference the source site and not have it called locally?
Secondly if it is important for you to track who is using what, then could you not reference that image as a https:// ?
Nothing super serious except every time I log into the admin my browser goes nuts over insecure references.