Please report bugs here. If you are unsure whether something is a bug or an expected behavior, please post it on the "Technical Support" forum instead, and wait for a moderator to handle/move the post.
When Copying code from WPF to cshtml5 I had to rewrite it because the ComboBox.SelectionChanged was not called in cshtml5. It is easy to work around but it would be nice if it behaves exactly like WPF.