Currently i am not using any other plug in for tool tip on mouse hover of grid row. I am using
$(\"#list\").setCell(rowid,\'Name\',\'\',\'\',{\'title\':\'my
Because in the next version of jQuery UI will be included Tooltip (see demo) I recommend you better to download it now from github and a little play with it.
I prepared the demo which change the tooltip for the second column of the grid and use HTML contain with custom class (I use in demo standard ui-state-highlight class) and custom animation effect (slideUp/slideDown). So you will see about following

I hope the demo will help you to implement your requirements to custom tooltips.