[flexcoders] Bar-chart gradient/color change depending on positive or negative value

[Joy]

Hi
  How do I apply different gradients to the bars (bar-chart),
depending on positive or negative values eg. +ve values shud have a
diff. gradient while negative should hav a diff. gradient.
  Also how do I make the 'showDataTips' draggable, so as to make
dynamic change on the data. I want the value displayed, eg. value 5
appears as tooltip, and can be dragged, to reflect the data-change.
  Thanks in advance