typedef void __fastcall (__closure *TSectionDragEvent)(System::TObject* Sender, THeaderSection* FromSection, THeaderSection* ToSection, bool &AllowDrag);
TSectionDragEvent is the type for event handlers that respond when the user drags a section in a header control.
Sender is the header control that includes the dragged section.
FromSection is the header section that the user is dragging.
ToSection is the header section currently in the position where the user dragged FromSection.
AllowDrag returns a value that indicates whether the header control repositions the headers to accommodate the user's drag. If AllowDrag is false on exit from the event handler, the headers remain in their original positions, as if the user had not tried a drag operation.