modifications to fix tests since changing window handles to tlbcs; fixes...

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This gets tests passing again, but doesn't integrate window switching/handling with our ui libraries nicely at all. I'm thinking we could have something like "find_opened_window()" in the browser class or a neighboring class that would return the new window handle when taking an action that results in a window opening to avoid the tedious pattern I have here. @whimboo, what do you think?
here we need a BaseWindow.close() method (if we don't have that yet)