well, because that expanding option for "window buttons" is
disappeared in this (4.10) version.
so You'd better to check below link and find "Window Buttons" section.
It will helps you. cheers
2012/5/22 Silvio Siefke <email@example.com>:
> have someone installed XFCE in Version 4.10 and can me tell, has same
> with the windows which are now in the back of the menupanel?
> Old: http://silviosiefke.de/img/ext/old.png
> New: http://silviosiefke.de/img/ext/new.png
> They are others Relation in Screenshots, one is my Netbook, other is my
> normal Notebook.