mozilla / seamonkey -- unable to install forecastfox for a regular user

[martinko]

hello!

since i discovered forecastfox extension i've been trying and unable to
install it on freebsd.  i've tried many times different versions of
mozilla suite and seamonkey now but to no avail.  i can install it for
root if the browser is run by root but when i try to install it as a
regular user the installation is canceled sometime in the end (that is
the extension is downloaded, maybe installation begin and then a window
displays a message saying installation canceled).  this has been the
case since freebsd 5.3 or 5.4, now i'm running 6.1.

does someone know how to solve this pls ??
any other thoughts or suggestions pls ??

cheers,

martin