setIndexWithFocus method
Implementation
void setIndexWithFocus(Index index) {
final ts = DateTime.now().millisecondsSinceEpoch;
if (index != indexWithFocus)
focusCount = 0;
else if (_focusTimeStamp == 0) {
focusCount = 0;
} else if (ts - _focusTimeStamp > 500) {
focusCount = 0;
}
_focusTimeStamp = ts;
indexWithFocus = index;
focusCount += 1;
}