Custom Control Properties in a group

I am creating a custom control for windows forms that is a derivation of the windows button control.  I m adding several properties to the control that a user can control in the properties form.  The control works perfectly but I would like to group my custom properties together.

I would like to group these properties together so that in the properties form there is a '+' on the left hand side that the user can see the new properties in one group.  This would be similar to how the font property is displayed in the property form.

I tried to add the individual properties to a class and to make the class accessible but I can't change the individual properties of that class.  Is there a better way to do this.