I'm extending the combobox control and in the constructor, I am performing a fetch to populate my items collection. The problem is, when I drag my control on the form, I get an exception, because the designer calls the controls constructor. Does anyone know if there is a way to check if executing in design time or runtime?

I'm no design time expert but I recall something with the Site property of the component: you can read that to check if you;'re in design mode or not.

Nice, thanks man!

 #If DEBUG Then
Public Class MDIFormBase
#Else
    Public MustInherit Class MDIFormBase
#End If

I use the above on my base form so the form design works correctly in the ide. I think you could do something similar for your constructor.