In gnus-sum.el, gnus attempts to add a tool-bar item for

(gnus-summary-tick-article-forward "flag-followup" nil :visible nil)

pointing to an image file "flag-followup" which is not supplied.

This does not have any ill effects as far as I can see, but perhaps  
it is not what's intended.
There is an image file called "followup" - is that the right file?


Also, I noticed that the icon in mail/save shows up differently from  
the rest - it has black bars on top and bottom and shows up  
differently when selected. (See attached screenshot. I tested this in  
a 22 branch build as well.) I have no idea what causes this behavior.