Hi, try to make an event in selecting the item, then filter "ALL"
Like this:
private void checkedListBox1_SelectedIndexChanged(object sender, EventArgs e)
{
if (checkedListBox1.SelectedItem.ToString() == "ALL")
{
checkedListBox1.Enabled = false;
for (int x = 0; x < checkedListBox1.Items.Count; x++)
{
checkedListBox1.SetItemChecked(x, true);
}
}
}