Newbie question: Activity diagram arrows

Hi,

 

I am running Umbrello 1.1.1 on SuSE Linux 8.2.

 

When I try to draw activity diagrams the arrows go directly from one
activity to another (diagonally), rather than going horizontally across
and vertically down as per the textbooks, and the user documentation.

 

I have searched the documentation, and the archives, but I can't find
out how to change the style of the activity diagram arrows.

 

Cheers,

 

Ewan