Hi,
I'm not sure I understand the problem.
You say : "...a simple CheckComboBox and it fails as well. "
Then : "....added the single line CheckComboBox you proposed and it works just fine. "
And then : "...the Package loads and the rest of the extension works just fine".
But there is an exception in the XAML designer.
I don't have any exception in the XAML designer for a single line CheckComboBox.
Can you provide a sample ?
I'm not sure I understand the problem.
You say : "...a simple CheckComboBox and it fails as well. "
Then : "....added the single line CheckComboBox you proposed and it works just fine. "
And then : "...the Package loads and the rest of the extension works just fine".
But there is an exception in the XAML designer.
I don't have any exception in the XAML designer for a single line CheckComboBox.
Can you provide a sample ?