Set the selection indexes
int PtGenTreeSetSelIndexes( PtWidget_t *widget, unsigned short const *buffer, int count );
This function sets the selection indexes. It assumes that buffer points to a sorted array of indexes. The first item in the widget has an index of 1, not 0.
The function returns the number of items that have been actually selected, which may be smaller than count if the array isn't sorted or contains duplicate or out-of-range indexes.
When the selection mode is Pt_SELECTION_MODE_RANGE, only the first index and the count are used.
The number of items actually selected.