For using the Drag Gadgets
struct DragInfo {
struct Gadget *Gadget; /* Gadget to drag */
SHORT LeftEdge, /* Bounding Box */
TopEdge,
RightEdge,
BottomEdge;
USHORT Flags; /* Command flags */
SHORT XPos, YPos; /* Current position */
void (*UpdateRoutine)(); /* User supplied routine */
LONG DD; /* Leave this alone */
};
How to initialize see here --> DragGadgets