User Control: Can't set property to Nothing at design time

[Ivan D.]

I am making a User Control in visual basic, it contains a
Picture Box. To allow the image to change at design time I
added a property.
When changing a *normal* PictureBox Image at design time
in the properties window the delete key usually sets the
Image to nothing, but when I tried this with my new
property it did not work.

I have a feeling something needs to be added to the
property statement in order to accept Nothing for any
object, but I did not find an article on this.

Here is my Property code, at least it allows me to change
the picture at design time:

Property CurrentImage() As Image

' Retrieves the value of the Image.
Get
Return PictureBox.Image
End Get

' Updates the value of the Image.
Set(ByVal NewImage As Image)
PictureBox.Image = NewImage
End Set

End Property

So what needs to be added? I just want to make the delete
key set the Image to Nothing at design time like most
natural components in visual studio can.
I have a work around set up, but I would like to know the
proper way to do this.

Thanks in advance.