Joining vertically adjacent cells

Joining vertically adjacent cells

I can easily join cells that are adjacent to each other horizontally (left-to-right). But when I mark cells that are vertically adjacent (top-to-bottom), even if they are in just one column, an attempt to join them is ignored, they remain separate cells.
I'm not sure whether this is a bug or a feature request, but it should work anyway.
I'm using Firefox 2.0.0.16 on Win XP Home 5.1.2600 SP2.
Thanks, Klaus