Last message header when scrolling down using scrollbar

[Thomas Maeder <maeder+balsa glue ch>]

I have a strange problem when scrolling down the header pane using the 
scrollbar down arrow: when the mailbox is rather largish (>500 
messages), the last header is often displayed incorrectly: it's 
impossible to read it, and it also doesn't seem to refer to a message. 
When I attempt to select that last header, Balsa regularly crashes.

It looks as if the header pane scrolls down one line too far under 
certain conditions (and that the number of messages is involved in 
these conditions). Has anybody else experienced this behavior, too?