[joe] Selection problem

If I select a large part of text (spanning a number of screens), then
it select few lines more. To make it more clear, let us assume I
pressed ^k+b at line number 68, then I jumped to line number 351 and
pressed ^k+k. Instead of selecting between lines 68 and 350, the
actual selection is between 67 (or 66) and 350.

How to avoid such selction. I am using Joe V2.8 on RedHat7.1

-- 
H.S.Rai