/// <summary>
/// In order to simplify dealing with multiple categories setting, clean
/// and hide the search window so that if new category will be typed, it
/// will start fro the beginning, without the necessity to clean the previously
/// typed characters.
/// </summary>
void _categoryTree_AfterThreeStateCheck(object sender, ThreeStateCheckEventArgs e)
{
if (e.CheckState == NodeCheckState.Checked)
{
_categoryTree.ClearSearchWindow();
}
}
