Hi, override the SetDefaultValues(ContentType contentType), call the base implementation and set your property value in the method like: type = "heavy"; The value is set when the block is created in edit mode (but not if you create it programmatically (well unless you call the methos)).

Also you can also implement the property getter in a way that it will return a default value if the value is null, like this:

get
{
   string setValue = this.GetPropertyValue(b => b.type);

   if(string.IsNullOrWhitespace(setValue))
   {
      // return a default value if nothing is set
      return "heavy";
   }

   return setValue;
}

(oh btw, as a side note, your property type should not be with lower case but Type with capital T)

I tried this, but it doesnt work unfortunately (tried cleaning and rebuilding the project). No idea why. Also tried using a different property name (MyType) in case it was reserved in some way.  When I create a new block of this type, the "Type" field is still blank, and I have to manually type in the fields value.

        public virtual string Type
        {
            get {
                string val = this.GetPropertyValue(b => b.Type);
                if (string.IsNullOrWhiteSpace(val)){
                    return "heavy";
                    } 
                return val;
            }
            set { type = value; }
        }

Just to clarify - that property overriding doesn't show the value in edit mode - you get that default value in your view for example if there is no value set by editor.

How about setting default value?

public override void SetDefaultValues(ContentType contentType)
{
	base.SetDefaultValues(contentType);
	type = "heavy";
}

It sets the value when you create the block, so you don't have to.