This is an updated version of the "Tooltip Icon Custom Control" from K2 France. All credit goes to K2 France for the original.
I had some troubles with the former project on 4.6.9 so I fixed them, upgraded to .NET 4.5.1 and made the control into an "input" control so that you could assign it return values from a smartobject call. I have not tested prior to 4.6.9.