Overview Map dissappears when on permalinked page

Originally reported in http://openlayers.org/pipermail/users/2007-January/000440.html

This is actually a problem with event listener splicing. Patch to follow.

I know that the overview map still isn't updated when you use a permalink, but that's a different ticket. This one just makes sure the control's draw method is called.

patch that clones the listeners array before executing callbacks

It is necessary to get a clone of the listeners array when an event is triggered because a callback may manipulate the listeners array before all of the listener functions are called (by unregistering an event). This means that the listeners.length changes during the execution of the for loop - leaving callbacks at the end uncalled. The overview map was listening for a changebaselayer event, but the listener never got called because the arg parser would splice the listener array - removing its own listener, shortening the array length, and leaving the last callback (the overview listener function) uncalled. Cloning the array with a slice() takes care of this.

All (relevant) tests pass in FF, IE, and Opera.

Happy to commit after review.

Wow, that's a nice catch.

Low impact patch. All tests pass (and we definitely test a fair number of event handling situations). Things still appear to work afterwards :) Go ahead to commit, should be pulled up for 2.3.

applied at r2164