IExternalFormHolder interface
The IExternalFormHolder interface represents the TExternalFormComponent object and holds the IExternalForm interface.
public interface IExternalFormHolder
Namespace: DXP · Assembly: Altium.SDK.Interfaces
Remarks
For example VCL technology is not compatible with MS C++ toolkit.
Therefore to work with windows in the Altium Designer platform, you use the IExternalForm interface to have access to windows and manipulate them.