private static void UndoCommand_CanExecute(object sender, CanExecuteRoutedEventArgs e)
{
//e.CanExecute = previousColor.HasValue;
ColorUserControl colorUserControl = (ColorUserControl)sender;
e.CanExecute = colorUserControl.previousColor.HasValue;
}
private static void UndoCommand_Executed(object sender, ExecutedRoutedEventArgs e)
{
//this.Color = (Color) previousColor;
ColorUserControl colorUserControl = (ColorUserControl)sender;
Color currentColor = colorUserControl.Color;
colorUserControl.Color = (Color)colorUserControl.previousColor;
}