calendar's left&right arrows

[Stefan Monnier]

The left&right arrows of calendar's main buffer (in the mode-line) work
oddly in two ways:

1- they only accept mouse-2 even though Emacs now usually accepts mouse-1
   as well for such buttons.
2- they work in the opposite direction from the one used by most/all
   horizontal scrollbars.  I understand both behaviors "make sense", but
   I find I always get confused by calendar's choice.


        Stefan