private CheckState CalculateToggledCheckState(OLVColumn column, CheckState currentState)
{
switch (currentState) {
case CheckState.Checked: return column.TriStateCheckBoxes ? CheckState.Indeterminate : CheckState.Unchecked;
case CheckState.Indeterminate: return CheckState.Unchecked;
case CheckState.Unchecked:
default: return CheckState.Checked;
}
}