virtualbox freebsd 9.1 guest, mouse not operational

[Norbert Beckmann]

 > Gnome enabled, I get a proper gnome login screen after boot, the mouse
 > pointer is there, but does not affect something.

Replying to my own post, I have to amend the following:

The movement and the position of the mouse pointer is even recognized by the
login screen and thus Gnome. This is obvious because these small pop-ups 
like
"Log in as .." appear when the mouse pointer moves over them.
Hence, the sole functionality missing is the communication between Gnome and
the mouse buttons.
So I should have written: "... the mouse (pointer) is recognized, but 
clicks do not
affect something."

Norbert