Actually it does sort of make sense, since using mshtml (embedded IE) gives you all sorts of things like parsing internet addresses. What they forgot to do was remove the mouse and keyboard handling. I've had to do something similar for an app I wrote - the UI was quite complex and the easiest way was to build it using css+html (we could not use XAML) so it used an embedded IE browser. There is a lot of messy code required to make sure you disable all the default behavior and keyboard+mouse shortcuts, otherwise you get fun stuff like hitting Alt+arrow and the UI changes :)

I'm a Roboform customer but switched to Lastpass a year ago and haven't looked back.