Rated 5 out of 5 stars
Today I installed this add-on on my PC at my workplace , too.
I realized that add-on "Tool Bar Buttons 1.0" was formerly installed,
this YesScript icon was missing.
At such a time as this , temporarily disable Tool Bar Buttons and restart the Firefox.
Then YesScript icon will appear in the customize window.
Once YesScript icon is put on the appropriate place,
you may enable Tool Bar Buttons.
Seek the icon Rated 5 out of 5 stars
Finally I found the icon.
At first, even in the customize window the icon was'nt exsist.
I deleted several addons including this yesscript.
And disposed of xpi files in the Extension folder.
Then restart the FF5.0.
Yet yesscript icon didn't appear in the addon bar(=status bar) in the initial state,
but in the customize window (right click at the empty place on the addon bar) I finally met the icon !!!
windows vista SP2