Scott,
You must not be doing something quite right, as this is how the BusinessObject property on ComboBoxes, ListViews, ListBox controls all work. When you go to select a BO, it shows you the sub-classed BOs you've dropped on your form. to demonstrate this, first create a sub-classed BD:
Public Class MyBrowseDialog
Inherits BrowseDialog
End Class
Then create a sub classed combo with a property for the a browse dialog:
Imports System.ComponentModel
Public Class MyCombo
Inherits ComboBox
Private _findBrowser As BrowseDialog
<Category("Example Property")> _
<Description("Select a browse dialog.")> _
Public Property FindBrowser() As BrowseDialog
Get
Return _findBrowser
End Get
Set(value As BrowseDialog)
_findBrowser = value
End Set
End Property
End Class
Note that the property is for a base class, or it could be for an interface. In either case, the property sheet in the designer UI will list all types in the parent form that are of that type or sub-classed from that type (after you've built the project with the combo and BD).
So, build the solution, then drop an instance of the combo and the BD on a form. The combo should now have a FindBrowser property (in the "Examle Property" category) with a drop down that included the subclassed BD.