Fully close an HTML widget, programmatically?

Hi,

I'm working on an iBook with a lot of HTML widgets, which are each pretty big on their own. When a opens, and then closes, about a dozen widgets, iBooks crashes. I assume this is due to memory issues and Safari simply can't handle all of them being open at the same time.

I can tell that they're open at the same time because if I close a widget and reopen the same one, it drops me back into the state that I left it in (it doesn't reset it). But I'm OK with it resetting, if it means the book doesn't crash.

Is there a way to write a widget in such a way so as to tell iBooks to fully close the embedded browser window when the user closes the widget? It is extremely annoying for users to have to deal with books that crash all the time.