How to check if i'm in run-time or design time?

Question

I developed some userControl that contain some information check on the \'IsVisible\' method ( override method ).

When i using this usercontrol on some window - i se

Answer 1

public partial class MainWindow : Window
{
    public MainWindow()
    {
        if (System.ComponentModel.DesignerProperties.GetIsInDesignMode(this))
            Console.WriteLine("The main window is in design mode.");
    }
}

The other answer is technically correct but I am providing this one to clarify the namespace and the usage.