Mouse track bug on staked bar chart

[fast95]

I join an example of mouse track bug for stacked bar chart.
On the three stacked bars, mouse track display 3 different results:
wrong value for d2
good value for d3
no value for d4

testpb.txt

[rutkas]

Yes, I approve that bug wih stacked bars and mouse still exist:

• Only first (sometimes only last) stack responses to mouse
• Red border appears long from the bar on response