I hadn't set that, but I didn't need to in any case (it is a simple object, an IParentContainer), so the default is fine.
However, it did prompt me to work up a sample app that eventually allowed me figure it out. In translating the code from VB to C#, I didn't correctly handle this line:
'-- In ComboBox code, ParentContainer Get
If (Not Array.IndexOf(CType(loDesigner.RootComponent, Object).GetType().GetInterfaces() _
, GetType(MicroFour.StrataFrame.UI.Windows.Forms.IContainerControl)) > -1) _
AndAlso (loDesigner.RootComponent IsNot Me) Then
The "Not Array.IndexOf(....) > -1" really was making my brain hurt in C# after adding all the parentheses to handle casting and I didn't do that right. I changed it to:
//-- Check the type of the root component - changed from Not > -1 to < 0.
if ((Array.IndexOf( ((object)(loDesigner.RootComponent)).GetType().GetInterfaces(), typeof( IContainerControl ) ) < 0)
&& (loDesigner.RootComponent != this))
Now it works correctly. I'm still trying to figure out how to debug code that is written for the designer...
Thanks for the help!