XPGetWidgetProperty
WIDGET_API intptr_t XPGetWidgetProperty(
XPWidgetID inWidget,
XPWidgetPropertyID inProperty,
int * inExists); /* Can be NULL */
This routine returns the value of a widget’s property, or 0 if the property is not defined. If you need to know whether the property is defined, pass a pointer to an int for inExists; the existence of that property will be returned in the int. Pass NULL for inExists if you do not need this information.