Volume 6A: Motif Programming Manual

int item_position;

XmString *selected_items;

int selected_item_count;

int *selected_item_positions;

char selection_type;

} XmListCallbackStruct;

The reason field specifies the reason that the callback was invoked, which corresponds to the type of action

performed by the user. The possible values for this field are:

XmCR_BROWSE_SELECT

XmCR_DEFAULT_ACTION

XmCR_EXTENDED_SELECT

XmCR_MULTIPLE_SELECT

XmCR_SINGLE_SELECT

The reason field is important with List callbacks because not all of the fields in the callback structure are valid for

every reason. For the browse and single selection policies, the reason, event, item, item_length, and

item_position fields are valid. For the default action, all of the fields are valid. List items are stored as compound

strings in the callback structure, so to print an item using printf(), we must convert the string with the compound

string function XmStringGetLtoR().

13.5.3 Multiple Selection Callback

When XmNselectionPolicy is set to XmMULTIPLE_SELECT, multiple items can be selected in the List widget.

When the user selects an item, its selection state is toggled. Each time the user selects an item, the callback routine

associated with the XmNmultipleSelectionCallback is invoked. the source code shows the

sel_callback() routine that could be used with a multiple selection List. XmFONTLIST_DEFAULT_TAG

replaces XmSTRING_DEFAULT_CHARSET in Motif 1.2.

void

sel_callback(list_w, client_data, call_data)

Widget list_w;

XtPointer client_data;

XtPointer call_data;

{ ...