XmDropSiteRegister — A Drag and Drop function that identifies a drop site and assigns resources that

XmDropSiteRegister identifies the specified widget or gadget as a drop site and sets resource values that
       define  the  drop  site's  behavior.  The  routine  assigns  default values to any resources that are not
       specified in the argument list.  The toolkit generates a warning message if a  drop  site  is  registered
       with XmNdropSiteActivity set to XmDROP_SITE_ACTIVE and the XmNdropProc resource is NULL.

       If  the  drop  site  is  a  descendant of a widget that is registered as a drop site, the XmNdropSiteType
       resource of the ancestor drop site must be specified  as  XmDROP_SITE_COMPOSITE.  The  ancestor  must  be
       registered  before  the  descendant.  The drop site is stacked above all other sibling drop sites already
       registered.

       widget    Specifies the ID of the widget to be registered.

       arglist   Specifies the argument list.

       argcount  Specifies the number of attribute/value pairs in the argument list (arglist).

       For a complete definition of DropSite and its associated resources, see XmDropSite(3).

XmDropSiteRegister  —  A  Drag  and  Drop function that identifies a drop site and assigns resources that
       specify its behavior  "XmDropSiteRegister"  "Drag  and  Drop  functions"  "XmDropSiteRegister"  "register
       functions" "XmDropSiteRegister"

XmDisplay(3),  XmDropSite(3),  XmDropSiteEndUpdate(3),   XmDropSiteStartUpdate(3),   XmDropSiteUpdate(3),
       XmDropSiteUnregister(3), and XmScreen(3).

                                                                                           XmDropSiteRegister(3)

       #include <Xm/DragDrop.h>
       voidXmDropSiteRegister(
       Widgetwidget,
       ArgListarglist,
       Cardinalargcount);