Another viable option would be Visual Tcl [2] for Tcl/Tk [3]. Given the event-based nature of Tcl and Tk, I find it matches well for a methodology like VB provided.
And it's far from the only one I remember (although you'll need to do some research here [4]). For example, Komodo IDE used to have a Tk GUI builder that provided for the same kind of methodology, which has been split off in [5].