Make all Controls on a Form read-only at once

Question

Does anyone have a piece of code to make all Controls (or even all TextBoxes) in a Form which is read-only at once without having to set every Control to read-only individua

Answer 1

In Form:

if (_cached == null)
{
    _cached = new List();

    foreach(var control in Controls)
    {
        TextBox textEdit = control as TextBox;
        if (textEdit != null)
        {
            textEdit.ReadOnly = false;
            _cached.Add(textEdit);
        }
    }
} 
else
{
    foreach(var control in _cached)
    {            
        control .ReadOnly = false;
    }
}

Add recursion also (Controls can be placed into other controls (panels)).