Helptext that you assign to fields is an extremely handy feature as it is helps the user get more information themselves instead of searching for particular training material.  It can help explain detailed business rules or the details of why/how a field is used.

We have found that two types of controls, images and reference controls do not have this capability.  Images can be used to provide some sort of visual indication to the user to do something, and reference controls are references to another table (ie. an explanation for Vendor, on the Purchase Order table. Helptext can be assigned within Visual Studio, but no helptext actually appears on the UI.

As a suggestion, we believe all helptext should be supported if assigned within Visual Studio, including Image and Reference Controls.