GetDesigntimeWarnings is called automatically at design time when the adapter page producer is assembling the current version of its HTML form. This gives the adapter control group an opportunity to add messages to the version of the HTML form that appears at design time, describing problems that you can rectify. 

If the Adapter property has not been set, GetDesigntimeWarnings adds a message that indicates this omission. Otherwise, GetDesigntimeWarnings adds a reference to Adapter to the design-time warnings object so that it can obtain any warning messages that the adapter wants to add. 

AWarnings is the design-time warnings object that assembles design-time warning messages that appear in the HTML form. 

Adapter 

TAdapterPageProducer