#GetMsg
Do something like:
WaitPort(req->UserPort);
mess = (struct IntuiMessage *)GetMsg(req->UserPort);
GadAddress = (struct Gadget *)mess->IAddress;
class = mess->Class;
ReplyMsg(mess);
…
case GADGETDOWN:
gad_id = GadAddress->GadgetID;
switch (gad_id) {
case SCROLL_GADGET:
do {
scroll_stuff();
} while (GadAddress->Flags & SELECTED);
break;