Volume 6A: Motif Programming Manual

The routine tests the callback structure's reason field to determine whether the callback was invoked as a result of a

multiple selection action or the default action. When the reason is XmCR_MULTIPLE_SELECT, we print the list of

selected items by looping through selected_items and selected_item_positions. With this reason, all

of the fields in the callback structure except selection_type are valid. If the reason is

XmCR_DEFAULT_ACTION, there is only one item selected, since the default selection action causes all of the other

items to be deselected.

13.5.4 Extended Selection Callback

With the extended selection model, the user has the greatest flexibility to select and deselect individual items or ranges

of items. The XmNextendedSelectionCallback is invoked whenever the user makes a selection or modifies

the selection. the source code demonstrates the sel_callback() routine that could be used with an extended

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;

{

XmListCallbackStruct *cbs = (XmListCallbackStruct *) call_data;

char *choice;

int i;

if (cbs−>reason == XmCR_EXTENDED_SELECT) {

if (cbs−>selection_type == XmINITIAL)

printf ("Extended selection −− initial selection: ");

else if (cbs−>selection_type == XmMODIFICATION)

printf ("Extended selction −− modification of selection: ");

else /* selection type = XmADDITION */

printf ("Extended selection ...