When you create a data editing control, you create and register the component and add the data link just as you do for a data browsing control. You also respond to data changes in the underlying field in a similar manner, but you must handle a few more issues. 

For example, you probably want your control to respond to both key and mouse events. Your control must respond when the user changes the contents of the control. When the user exits the control, you want the changes made in the control to be reflected in the dataset. 

The data editing control described here is the same calendar control described in Creating a data browsing control. The control is modified so that it can edit as well as view the data in its linked field. 

Modifying the existing control to make it a data editing control involves:

• Changing the default value of FReadOnly.
• Handling mouse-down and key-down messages.
• Updating the field data link class.
• Modifying the Change method.
• Updating the dataset.