ExtJS 4.2.1 grid field with tooltip
<p>I'm trying to get a hover/tooltip effect for some text in an ExtJS (4.2.1) grid.
For some reason, the tooltip <code>span</code> is being occluded by the pretty much everything else.</p>

<p>Seems to be an issue with stacking, but I'm not sure the best way to bring the <code>span</code> in front of everything else (other rows, and the frame surrounding the grid).</p>

<p>Fiddle:<br>
<a href="https://jsfiddle.net/z3jj601f/" rel="nofollow">https://jsfiddle.net/z3jj601f/</a></p>

<p>I tried using z-index to no avail.
Can anyone tell me the right way to bring the tooltip span to the absolute foreground?</p>