You can test for design-mode by using the following code:

public InheritanceTree(){
    if (this.Site==null || !this.Site.DesignMode){
        throw new Exception("");  // Because we are in run-time mode.
    }
}

--
Bryan Phillips
MCT, MCSD, MCDBA, MCSE
Blog:  http://bphillips76.spaces.live.com
Web Site:  http://www.composablesystems.net

Hi,

Let's say we have a base form and an inherited form. When the inherited
form is opened in the designer, an instance of the base form is created --
the designer calls the default constructor of the base form to create the
instance and this is why a default constructor is needed.

Generally speaking, we could judge whether it is at design-time or run-time
through the DesignMode property of the form. The DesignMode property
depends on the Site property to determine design-time or run-time (at
run-time, the Site property is null; otherwise, the Site property has a
value).

Note that it's early to judge design-time or run-time using the DesignMode
property in the constructor, because the instance has not finished the
construction and the Site propery has NOT been assigned at this time.

I suggest that you add a public field of type bool in your project to
denote design-time. The default value of this field is false. Set the
field's value to true in the static Main methd. The following is a sample.

   class Program
   {  
       public static bool IsDesignTime = true;  
     
       [STAThread]
       static void Main()
       {
           Application.EnableVisualStyles();
           Application.SetCompatibleTextRenderingDefault(false);
           IsDesignTime = false;
           Application.Run(new derivedform());
       }
    }
   public partial class baseform : Form
   {
         public baseform()
         {
           if (!Program.IsDesignTime)
           {
               throw new Exception("this construtor can't be called at run
time!");
           }
           else
           {
               InitializeComponent();            
           }
       }
    }
         
Hope this helps.
If you have any question, please feel free to let me know.

Sincerely,
Linda Liu
Microsoft Online Community Support

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