ArcGIS Engine Developer Guide

C++ APPLICATION PROGRAMMING INTERFACE
To get the number of clicks, you must access the call_data, which has the type
XmPushButtonCallbackStruct. To do so, you will need to cast the XtPointer to this
callback struct type, then you can get the integer member click_count.
void ClickCallback(Widget w, XtPointer client_data, XtPointer call_data)
{
XmPushButtonCallbackStruct* data = (XmPushButtonCallbackStruct*) call_data;
std::cerr click_count