I know Webview only as a C# MS control to display HTML contents (to integrate browsing web in an application).
The only visible connection to VAST is the blue icon, the shown contents is definitively not Smalltalk (being a typed language), nor a VAST image.
I cannot recognize which application is shown here in the attached picture.
Can you declare what application you are using?
The absence of VAST specific callbacks seems to be obvious (for me).
Kind regards
Marcus