Question

In .NET framework, is it possible to set some of the items in the CheckedListBox as ‘uncheckable’ ? I don’t want to allow user to check the same items again and add them to a another existing list.

I hope I am clear. Thanks in advance.

Answer 1

I would set those items as ‘Indeterminate’ in code, and then overwrite the ‘NewValue’ property from the ItemCheck event when the user attempts to check/uncheck them:

public Form1() {     InitializeComponent();     checkedListBox1.Items.Add('Can't check me', CheckState.Indeterminate); }  private void checkedListBox1_ItemCheck(object sender, ItemCheckEventArgs e) {     if (e.CurrentValue == CheckState.Indeterminate)     {         e.NewValue = CheckState.Indeterminate;     } } 

The ‘Can’t check me’ item in the CheckedListBox can’t be modified, because every time the user tries to check/uncheck it, the event handler changes it back. You don’t even see the UI update accordingly.