sub BindMouseWheel {
   my ($w) = @_;
   if ($^O eq "MSWin32")
   {
      $w->bind('<MouseWheel>' => [ sub { $_[0]->yview('scroll', -($_[1]/120)*3, 'units') }, Ev('D') ] );
   }
   else
   {
      # Support for mousewheels on Linux commonly comes through
      # mapping the wheel to buttons 4 and 5. If you have a
      # mousewheel ensure that the mouse protocol is set to
      # "IMPS/2" in your /etc/X11/XF86Config (or XF86Config-4)
      # file:
      # Select "InputDevice"
      #     Identifier "Mouse0"
      #     Driver "mouse"
      #     Option "Device" "/dev/mouse"
      #     Option "Protocol" "IMPS/2"
      #     Option "Emulate3Buttons" "off"
      #     Option "ZAxisMapping" "4 5"
      # EndSection
      $w->bind('<4>', => sub {
         $_[0]->yview('scroll', -3, 'units') unless $Tk::strictMotif;
      });
      $w->bind('<5>' => sub {
         $_[0]->yview('scroll', +3, 'units') unless $Tk::strictMotif;
      });
   }
}