private void Properties_PropertyChanged(PropertyPage props, int idx, object value)
{
if (idx == 3) // 3 = pattern length.
{
var barLengths = GenerateBarLengths((int)value);
var barIdx = Array.IndexOf(barLengths, selectedSong.BarLength);
if (barIdx == -1)
{
barIdx = barLengths.Length - 1;
}
props.UpdateDomainRange(4, barLengths, barLengths[barIdx]); // 4 = bar length.
}
}