List<Integer> rowPositions = RowGroupUtils.getRowPositionsInGroup(
rowGroupExpandCollapseLayer, rowIndexes);
ILayerEvent event;
if (wasCollapsed) {
event = new ShowRowPositionsEvent(rowGroupExpandCollapseLayer,
rowPositions);
} else {
event = new HideRowPositionsEvent(rowGroupExpandCollapseLayer,
rowPositions);
}