Bug in Thunderbird port?

[KMK]

Hello,

I use Mozilla Thunderbird version 1.5.0.8 (20061110) compiled from ports, on 
FreeBSD 5.5. I noticed the following wrong behaviour:

when the Thunderbird fileselector appears, e.g. after clicking on "Attach" 
button while composing a mail, or in any other circumstance, clicking on the 
slider at the right side of the selector in order to scroll the file list down, 
crashes the Thunderbird. The same happens, when the down arrow is clicked (and 
not the slider) and when the list is attempted to be scrolled using keyboard 
cursor keys (without any mouse action). This behaviour is independent from the 
contents of the directory that is being listed in the selector.

The error that occurs is Bus Error (signal 10).

I noticed this behaviour some time ago, I refreshed my ports tree and recompiled 
them (portupgrade -a) twice since (last time 9th December), but the error persists.

I use KDE as my window manager, if that matters.

Gtx,
KMK