Databindings custom variable.

I suspect you're missing something else here, David, which is a way for the myClass object to notify bound controls that its someVariable property has changed.

If you're using .NET 2.0 or later this can be done by MyClass implementing the System.ComponentModel.INotifyPropertyChanged interface. All you need to do is to change the code for MyClass as follows (everything else is taken care of behind the scenes):

    public class MyClass : INotifyPropertyChanged
    {
        public event PropertyChangedEventHandler PropertyChanged;

        private void NotifyPropertyChanged(string prop)
        {
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs(prop));
            }
        }

        private string someVar = "abc";

        public string someVariable
        {
            get { return someVar; }
            set
            {
                someVar = value;
                NotifyPropertyChanged("someVariable");
            }
        }

       // other code
    }

The most likely reason for this problem, David, is that someVariable is a field rather than a property. It has to be a property of an object for databinding to work.

Also I take it you've used an object variable rather than the class name for the second parameter?