Hi Ferdinand,

You will need to create a custom Designer for your Control.

In order to design your derived control, the Designer must first create
an instance of the base control class at design time. Since you've
declared the base abstract, it can't do that, so it can't provide you
with a design surface to work on.

So, no, you can't design controls derived from abstract classes.

The closest you can come is to test the DesignMode property in your
base calss (after your constructor... typically in your OnLoad method
or something like that) and, if it's false, throw an
InvalidOperationException. That way you know that your base class will
never be instantiated at run time.